FOUS30 KWBC 180802
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
402 AM EDT Thu Sep 18 2025

Day 1 Valid 12Z Thu Sep 18 2025 - 12Z Fri Sep 19 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF
SOUTHERN CALIFORNIA AND SOUTHWESTERN ARIZONA...

...Southwest U.S...

Remnant moisture from post-tropical cyclone Mario will continue to advect poleward with California firmly in the cross-hairs for elevated
moisture (PWATs 2-4 deviations above normal) to move into the
southern half of the state during the entirety of the D1 period.
Energy from Mario will lag the initial low to mid-level moisture
surge, but eventually will enter into the area by the late-morning
hours today, prompting an uptick in the areal coverage of
convection over the southern half of the state into the Lower
Colorado Basin between CA/AZ. The last succession of HREF runs,
including this evenings 00z suite was pretty pronounced in the
indication of precip totals between 2-4" potentially impacting some
of the coastal ranges of CA into the adjacent valley just north of
the Transverse and Peninsular Ranges. There's also a pretty good
indication of scattered to widespread convective development later
this morning, through the afternoon period across the lower deserts
of southeast CA to the neighboring Colorado Basin at the CA/AZ
line. This was the area of greatest change when it came to the
magnitude of the signal when assessing the run to run differences
over the past iterations of the HREF suite. Ensemble bias corrected
QPF was also adjusted upward from its previous forecasts across the aforementioned area, a testament to the improving signature for
local flash flood prospects in that general area. HREF neighborhood
probs for >1" across the deserts are upward of 50-80% now with
70-90+% located within the Transverse and Peninsular Ranges during
the period, a reflection of the heightened threat for at least
moderate rainfall, enough to spur high runoff concerns in the
terrain with several burn scars still present in-of those mountain
chains. Rates will be sufficient considering the deep moist
environment brought on by the advection of the tropical moisture
flux involved with Mario, another reason for the threat to be
leaning towards the higher side as elevated rates are a significant
driver to flash flooding historically across CA.

The previous SLGT was expanded a bit to account for the trends in
hi-res guidance and the conditioning of the environment favoring
the higher moisture anomalies being advected further north into CA.
The threat is on the higher end of the SLGT threshold with the
"saving grace" in this entire setup being the more progressive mean
flow helping push everything through in relatively faster time than
what is customary for higher level risks. That still doesn't deter
the fact that scattered flash flood prospects are becoming more
certain in the the areas outlined in the SLGT risk with a potential
for targeted upgrade plausible if conditions warrant.

...Central U.S...

Current WV satellite depicts a broad upper low (ULL) with the center
positioned over SD with a surface low analyzed almost underneath
the ULL meaning the confidence in an occlusion process beginning
soon is very high. Once we see the occlusion phase begin, we'll see
the slow degradation of the prominent deformation field across the
Dakotas over the course of the forecast leading to decreasing
rates and expected totals compared to what transpired the period
prior. As a result, flash flooding concerns will be relatively
isolated given the more stratiform rain process with the convective
threat positioned further east into the Mississippi Valley. 00z
HREF was not very robust for heavy rain prospects in any one area,
but there were several locations that will stand to benefit from
locally heavier convection as the cold front continues to migrate
eastward and drive a broad surface ascent pattern downstream of the
low. A few stronger mid-level vorticity maxima will help amplify
the threat in a few areas, mainly in the Missouri and Mid-
Mississippi Valleys later this afternoon as a stronger mid-level
shortwave continues to propagate into the region from its overnight
trajectory. HREF blended mean QPF distribution outlines this area
fairly well and matches with the modest >3" probabilities situated
over eastern OK up into MO. Overall, the entire setup with a slowly
decaying, or steady state low will contribute just another period
of widely scattered flash flood prospects from the Northern Plains
over and through the northern two-thirds of the Mississippi Valley.
The previous MRGL was general maintained with some adjustments
based on the latest hi-res ensemble probs and blended mean QPF footprint.

...Southeast Florida...

PWATs across south FL remain elevated with KEYW and KMFL both
coming in with values of 2.08" and 2.19", respectively meaning the
deep layer moisture forecast the past several days is firmly
entrenched over the region. Several shortwave perturbations will
advect northeast out of the Florida Straits and nearby Cuba with
the presence of a Cuban outflow being picked up in the radar/sat
composite over the past few hours. This is actually well-forecast
via some of the CAMs suite, a likely indicator that the future
trends within the models probably hold merit for a threat of heavy
rain to cross into the Key and the southern Peninsula in the early
morning hours. As the boundary migrates to the northeast, expect
copious showers/storms to gallivant through the area dropping
locally enhanced rainfall with rates between 2-3"/hr pretty much a
given in a few of the convective cores just due to the environment
in place. Models are still in flux on the exact locations of where
heavier rain will occur, but the neighborhood probs for >3" running
between 50-80% and >5" between 25-35% across both the Keys and
southeast FL are sufficient for a continuation of the previous MRGL
risk through the forecast cycle. Will monitor closely for potential
targeted upgrades, but the setup is certainly favoring at least
isolated flash flood potential within those two corridors,
particularly more urban zones due to impervious surface runoff.

Kleebauer


Day 2 Valid 12Z Fri Sep 19 2025 - 12Z Sat Sep 20 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE
CENTRAL SIERRA NEVADA AND CENTRAL VALLEY OF CALIFORNIA...

...California...

Remnant energy from what is left over from Mario will pivot up into
Central CA early Friday allowing for a continuation of heavy
rainfall prospects over the region as PWATs surge to between 3-4
deviations above normal. Guidance is keying on prevailing upslope
flow and focused ascent within the Central Sierra of CA with a
myriad of thunderstorms lingering in the Central Valley. The
environmental conditions favor locally enhanced convective cores
which could spell problems for those towns in the valleys, as well
as runoff in the terrain. HREF neighborhood probs for >1" are very
high (70-90%) within the above areas with mainly modest >2" probs
centered over the Central Valley and adjacent Sierra foothills.
Considering some overlap of heavy rain from D1 into D2, the threat
seems worthy of a targeted upgrade in these two zones to account
for the continued risk bleeding from period to period. The good
news is the setup looks to wane the second half of the forecast
cycle as energy pushes out of the region and we see a slow
improvement in the moisture anomalies. This would spell the end
for the threat of flash flooding and much of the rain prospects.

...Southwest...

Moisture increases across all of the Southwest CONUS will aid in
favorable environmental conditions for locally heavy convective
rainfall during the period of diurnal heating on Friday into early
Saturday. HREF mean QPF is relatively tame overall, but some of the
CAMs are more robust in their depictions of isolated 2+" totals,
especially across the Mogollon Rim and Southeast AZ terrain leading
to a broad MRGL risk maintenance from previous forecast. The
threat for flash flooding will likely lie as far north as the
I-70/15 junction and points west over UT/NV with slot canyons and
dry arroyos as the primary targets for flash flooding as is
customary in these setups. The threat for a targeted upgrade is on
the table, but will need to assess the evolution of the mid-level
vorticity maxima ejecting out of CA to the east over the course of
time. The most favored areas will likely be those outlined above.
For now, the MRGL risk will suffice.

...Mississippi Valley to ArkLaTex...

Occluded low over the Upper Midwest will continue to spin with a
dumbbelling mid-level shortwave pivoting southeast out of the
Dakotas allowing for a secondary broad ascent pattern to
materialize downstream over the Mississippi Valley. To the south,
thunderstorms will fire along a decaying front positioned over the Mid-Mississippi Valley down into the ArkLaTex with ample
instability and moisture to fuel another isolated flash flood
threat when assessing individual CAMs and ensemble bias corrected
outputs. The threat is similar to the previous period, perhaps even
a touch less robust considering the occlusion phase well in
progress by this point in the forecast. Overall, this threat was
deemed enough for a broad MRGL risk to stay in place, but there's
some potential for a targeted upgrade, pending better overlap from
model guidance on any particular area from TX to the Upper Midwest.

...Southeast Florida...

The southeast coast of Florida will be hanging on to the last bit
of remaining anomalous moisture as the pattern starts to shift away
from persistence of the preceding three periods. The MRGL was
maintained given some of the guidance hanging on to heavier
convection right along the coast with modest probabilities for >3"
lingering from Miami up to Daytona Beach. That was enough to
maintain continuity of a MRGL for at least one more period.

Kleebauer


Day 3 Valid 12Z Sat Sep 20 2025 - 12Z Sun Sep 21 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL AND SOUTHERN PLAINS INTO THE MISSOURI VALLEY...

...Central U.S...

Shortwave ejection out of the Great Basin/Four Corners area will
migrate into the Central and Southern Plains by Saturday afternoon
providing a more focused large scale ascent pattern during peak
diurnal instability. Ensemble means are relatively modest in their
QPF distribution and magnitude, signaling 1-2" of rainfall
currently in their depictions. Individual deterministic is
certainly a little more robust, but nothing that would promote a
more substantial risk. This correlates well with moisture anomalies
hovering between normal and +1 deviations when assessing the latest
NAEFS meaning the threat is warranted, but well-within the
threshold of a MRGL risk. As a result, kept the previous MRGL risk
and expanded to account for some uncertainty in the spatial
coverage of expected convection by this time frame.

Kleebauer
$$
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FOUS30 KWBC 190811
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
411 AM EDT Fri Sep 19 2025

Day 1
Valid 12Z Fri Sep 19 2025 - 12Z Sat Sep 20 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF THE
CENTRAL SIERRA NEVADA...

...California/Great Basin...

Remnant energy from Mario will continue to lift north across
California and become sheared by an upstream low over the Pacific,
with some energy wrapping back offshore, while the remainder
moves east into the Great Basin. This energy, along with highly
anomalous moisture (+4 std dev above normal), is expected to
continue to produce showers and storms early in the period across
parts of California, including the Sierra Nevada. While forecast amounts
have trended down, there is still some signal for locally heavy
rain to continue early in the period across portions of the central
Sierra Nevada. A small Slight Risk was maintained, mostly for the
initial 6-hours, where the HREF shows higher probabilities for
additional amounts exceeding an inch. By the afternoon, as the mid
level energy and greater moisture anomalies move east, expect the
greater chance for heavier rain to begin to focus over central
Nevada, where the HREF is showing a broader footprint of high
probabilities for amounts over an inch.

...Southwest...

Expect widespread coverage of showers and storms today, as moisture
from Mario bolsters PWs across the region. The general consensus of
the CAMs show greater coverage across eastern Arizona and western
New Mexico during the afternoon, before storms move southeast into
southeastern New Mexico and West Texas by this evening. Storm
motions are expected to generally progressive, limiting the threat
for widespread heavy amounts and flooding. However, there is some
signal for backbuilding and training, which could raise at least
isolated runoff concerns. HREF neighborhood probabilities for
amounts exceeding an inch are above 50 percent within much of the
Marginal Risk area.

...Upper Mississippi Valley/Midwest to the Lower Missouri Valley...

A mid-to-upper level low/negatively-tilted upper trough will
continue to move slowly east from the northern Plains into the
upper Mississippi Valley this period. While not expected to be a
widespread heavy rainfall event, south-to-north training storms
ahead of the associated occluded front, may produce locally heavy
amounts and isolated flooding from northern Illinois back across
the upper Mississippi Valley. The HREF shows widespread high
probabilities for amounts exceeding an inch across this region,
with some localized high probabilities for amounts over two inches.

Meanwhile, shortwave energy diving southeast out of the northern
High Plains, is expected to produce a secondary area of organized
amounts, with some locally heavy amounts possible from
southeastern Nebraska into southwestern Iowa and northwestern
Missouri this evening into the overnight. Here also, the HREF is
showing high probabilities for amounts over an inch, with heavier
amounts possible.

...Central Plains...

Energy moving through the base of the previously noted upper
trough, interacting with deepening moisture along a strengthening
low level jet is expected produce showers and storms developing
and dropping southeast across Kansas, with locally heavy amounts
possible by this evening. HREF probabilities indicate localized
amounts of an inch or more are likely, with heavier amounts
possible.

Pereira


Day 2
Valid 12Z Sat Sep 20 2025 - 12Z Sun Sep 21 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF SOUTHEASTERN KANSAS AND NORTHEASTERN OKLAHOMA THROUGH THE OZARKS...

Storms developing late in the previous period across Kansas may
continue, producing locally heavy amounts across portions of the
Ozark Region Sunday morning. Redevelopment is possible back to the
west later in the day as shortwave energy emanating from the west
moves into the region and interacts with deepening moisture
afforded by strengthening southerly flow.

Pereira


Day 3
Valid 12Z Sun Sep 21 2025 - 12Z Mon Sep 22 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHWEST AND FROM THE OZARKS THROUGH THE MID MISSISSIPPI VALLEY...

...The Southwest...

An upper low off of the California coast will drift southeast,
supporting the return of deeper moisture spreading north across
Arizona and western New Mexico on Sunday. With PW anomalies
increasing to 2-3 standard deviations above normal, numerous showers
and storms, producing locally heavy rainfall amounts and isolated
flooding concerns, can be expected.

...Ozarks through the Mid Mississippi Valley...

A broad upper trough will drift slowly east from the Plains into
the Mississippi Valley this period. A series of mid level
shortwaves lifting along the leading edge of the trough,
interacting an axis of deeper moisture is expected to produce showers
and storms with periods of heavy rainfall possible.

Pereira
$$
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FOUS30 KWBC 200821
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
421 AM EDT Sat Sep 20 2025

Day 1
Valid 12Z Sat Sep 20 2025 - 12Z Sun Sep 21 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE MIDWEST, THE SOUTHERN PLAINS, OZARKS, AND THE CENTRAL
APPALACHIANS...

...Wisconsin and northern Illinois...

A negatively-tilted upper trough will lift slowly across the mid to
upper Mississippi Valley today. The associated ascent interacting
with a ribbon of relatively deeper moisture (PWs 1.25-1.5 inches)
along a modest low level jet will support showers and storms
redeveloping this afternoon, which may potentially continue into
the evening. With differences in the details, the CAMs generally
indicate two areas of locally heavier amounts -- a north-south axis
associated with storms lifting across eastern Wisconsin during the afternoon/evening and a west-east stripe produced by storms
developing across Iowa and then training across northern Illinois
later during the overnight. HREF neighborhood probabilities
indicate localized amounts in excess of 2 inches are possible in
these areas.

...Ozarks to southwestern Oklahoma....

CAMs indicate that ongoing convection firing north of a stationary
front over southern Kansas will continue through the late morning,
potentially producing heavy amounts as they train further east
into the Ozark Region. The HREF shows high neighborhood
probabilities for accumulations over 2 inches centered over this
region.

Then, as upstream energy sliding southeast across the central
Plains interacts with deepening moisture that will be supported by
increasing southerly low level flow, some guidance indicate that
storms will redevelop over this same area later today. However,
other models show storms developing further to the west before
moving back into areas impacted by this morning's storms.

While there is fair amount of uncertainty on how these storms
across central into eastern Oklahoma will evolve, there is greater
model consensus that storms developing over the Texas Panhandle and
western Oklahoma by this evening will merge across southwestern
Oklahoma to produce locally heavy amounts across the region during
the overnight.

...West Virginia...

CAMs continue to show isolated heavy amounts associated with slow-
moving storms that are expected to develop over eastern West
Virginia this afternoon. A weak impulse lifting northeast out of
the Ohio Valley, interacting with pooling moisture along a slowing
front, will support storm development. HREF neighborhood
probabilities indicate that amounts of 2-3 inches are likely within
the highlighted area.

Pereira


Day 2
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL PLAINS, MID MISSISSIPPI VALLEY, AND THE SOUTHWEST...

...Eastern Kansas and northeastern Oklahoma to southern Illinois...

Deepening moisture (PWs above 1.5 inches) along an axis of
strengthening southerly to southwesterly flow ahead an amplifying
upper trough will fuel showers and storms, possibly producing
heavy amounts. While models differ significantly on the details,
the general consensus indicates widespread precipitation is likely,
with locally heavy amounts of 1-2 inches possible.

...Southwest...

An upper low dropping to the south along the California coast will
slow as it becomes cutoff west of Southern California. Southerly
flow ahead of the system will support increasing moisture and the
chances for precipitation across parts of Southern California and
Arizona. Both the GFS and ECMWF show PW anomalies increasing to 2.5
to 3 standard deviations above normal across far Southern
California through the lower Colorado Basin into Arizona.

Pereira


Day 3
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHWEST AND FROM KANSAS AND OKLAHOMA TO THE OHIO VALLEY...

...Kansas and Oklahoma to the Ohio Valley...

Unsettled weather will continue, with the footprint for potentially
heavy rain expanding as energy moving through the base of a broad
upper trough interacts with deep moisture that will be supported
persistent southwesterly flow. While models generally agree on a
large footprint of moderate to heavy amounts, they lack agreement
on the details. At least locally heavy amounts are expected,
especially within the western portions of the highlighted area as
a well-defined shortwave dives southeast and is expected to
interact with a pool of deepening moisture along a strong
southwesterly low level jet. Given the indication of 2-3 inches in
some of the models, which is forecast to fall in addition to the
previous days' amounts, an upgrade to a Slight Risk may be
forthcoming if the signal persists and the guidance moves into
better agreement.

...Southwest...

An upper low is forecast to remain cutoff and drift slowly east
along the Southern California coast. Anomalous moisture in place
across Arizona is expected to spread east into parts of New Mexico,
extending the chances for showers and storms, with potentially
heavy amounts into the region.

Pereira
$$
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FOUS30 KWBC 210821
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
421 AM EDT Sun Sep 21 2025

Day 1
Valid 12Z Sun Sep 21 2025 - 12Z Mon Sep 22 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN THE VICINITY OF
THE KANSAS/OKLAHOMA/ARKANSAS/MISSOURI BORDER AREA...

...Central-Southern Plains into the Mid Mississippi Valley...
Additional shortwave energy will be diving east southeastward
through the base of the mean trof centered through the Central to
Southern Plains into the Middle Mississippi Valley. These height
falls will help strengthen the low level west south west to
southwesterly flow into a west to east northeasterly oriented low
level boundary stretching from the Southern Plains into the Middle
Mississippi Valley. This will support another round of convection
pushing east from central to eastern KS/OK into much of MO,
northwest AR and central to Southern IL. A slight risk area was
added in the vicinity of the KS/OK/AR/MO border area that has seen
heavy rains over the past 24 hours and may see additional heavy
totals later in the upcoming day 1 period. Otherwise, there were no
significant changes made to the previous marginal risk area, that
continues to fit well with the latest axis of high HREF
neighborhood probabilities for 1 and 2"+ amounts during the
upcoming day 1 period. Across these areas, relative soil moistures
remain very low, which should help mitigate runoff issues, at least initially.

...Southern California into Arizona...
The closed low initially off the Central California coast will be
drifting only slowly southward day 1 to a position off the
Southern California coast. A jet streak on the eastern side of this
upper trof will keep favorable right entrance region jet dynamics
over Southern CA into Arizona. This will help accentuate lift in
an axis of anomalous PW values, 1 to 3+ standard deviations above
the mean that are expected to persist across these areas day 1.
This should support potential for additional widespread scattered
convection, locally heavy rains and isolated runoff issues.

Oravec


Day 2
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE
CENTRAL TO SOUTHERN PLAINS, MIDDLE TO LOWER MISSISSIPPI VALLEY AND
OHIO VALLEY AND ACROSS ARIZONA INTO WESTERN NEW MEXICO...

...Mid to Lower Mississippi Valley into the Ohio Valley...
The height falls pushing east southeastward day 1 into the Central
to Southern Plains and toward the Mid Mississippi Valley will
continue to move eastward through the Ohio Valley day 2. Well
defined large scale lift in an axis of above average PW values, 1
to 1.5+ standard deviations above the mean, will support the
likelihood of widespread moderate to heavy precipitation in an
axis from northern AR, far southeast MO, far southeast IL, western
to central KY, much of IN and OH. At the moment the convection
across these areas may be fairly progressive. This and very low
relative soil moistures, much of the area in moderate to severe
drought, will keep the risk level at marginal for the time being.
With respect to changes to the previous issuance, the northern edge
of the marginal risk was trimmed to the south by about 50-75 miles
to account for the latest model consensus.

...Central to Southern Plains...
The marginal risk area from the previous issuance was expanded
slightly westward into western KS to cover the model spread with
the next round of convection forming ahead of the upstream
amplifying height falls dropping southeastward late
day 1 from the Northern Rockies into the Central Rockies/Lee of the
Central Rockies on day 2. The GFS and NAM begin to diverge day 2
with the track of this closing off mid to upper level center, with
the NAM taking a more southeastward track into the Central Plains,
while the GFS takes a more south southeastward track into the
Central Rockies. The NAM solution, at the moment, is an outlier
with the EC, UKMET and CMC more in line with the GFS. The
differing mid to upper evolutions have more of a qpf impact over
south central WY into north central CO, where the more southeast
NAM solution is much lighter than the remainder of the guidance. Do
not believe there will be any runoff issues farther northwest
across CO/WY given lack of instability. While models differ farther
to the southeast, there are still non NAM solutions that have
potentially heavy rains as far northwest as northwest KS day 2,
supporting the west northwest expansion from the previous issuance.

...Southwest...
The closed low off the Southern CA coast day 1 is expected to move
little on day 2. The right entrance region of the jet streak to
the east of this closed low will push eastward from its day 1
position, but continue to support uvvs enhancement in the above
average PW axis, 1 to 3 standard deviations above the mean, that
will remain in place across Southern CA into the Southwest.
Additional scattered convection across these areas will support
localized heavy amounts and isolated runoff issues. The previous
marginal risk area was expanded westward into southeast CA to cover
the model qpf spread.

Oravec


Day 3
Valid 12Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, NORTHERN ARKANSAS, NORTHEAST OKLAHOMA AND SOUTHEAST KANSAS...

There continues to be model differences in the evolution of the mid
to upper level trof over the Central to Southern Plains toward the
Mid Mississippi Valley. The NAM continues to be an outlier in being
more amplified and faster to push the height falls downstream.
Despite the differences, models do show re-strengthening of the low
level southwesterly flow ahead of surface low pressure moving east
across Oklahoma into Arkansas. This will support potential for
organized convection, that likely forms late day 2 to the north of
this low across the Central Plains, continuing day 3 from southeast KS/northeast OK, across Southern MO and northern AR. Model
consensus is for the heaviest totals across these areas with
amounts of 2-4" possible. This heavy axis will possibly overlap
where heavy rains have fallen over the past 24 hours and where
additional heavy rains are possible during the day 1 period. There
were no major changes to the slight risk area from the previous
issuance. The marginal risk was extended farther westward into
northeast CO where several models show heavy rain potential day 3.
The eastern portion of the marginal risk was also extended into the
Upper OH Valley to cover the model qpf spread.

...Southern to Central California...
The nearly stationary closed low off the Southern CA coast day 2
will begin to slowly move back to the north on day 3 toward the
Central CA coast. This slow north movement will also allow for a
northward expansion of the anomalous PW values over Southern CA
into Central CA, with values as high as 3-4 standard deviations
above the mean. There are differences with qpf distributions given
differences with the northward push of the closed low. Not a lot
of confidence in any solution at this range, but continued
potential for locally heavy rains and isolated runoff issues,
especially over any burn scars. No changes made at the moment to
the previous broad marginal risk area over Southern to Central CA.

Oravec
$$
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FOUS30 KWBC 220821
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
421 AM EDT Mon Sep 22 2025

Day 1
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTH
CENTRAL KANSAS INTO NORTH CENTRAL OKLAHOMA...

...Central to Southern Plains...
The latest model suite is in better agreement with the evolution
of the amplifying upper trof across the Northern to Central Rockies
day 1 and the downstream outbreak of organized convection along
and to the north of the path of the associated surface low moving
west to east from the TX Panhandle into western OK. A slight risk
area was added for the potential for organized convection along and
to the north of this low, across areas of south-central KS into
north-central OK where the low level southerly flow will be
strengthening and the corresponding 850-700 mb moisture flux
becoming anomalous, upwards to 2 to 3 standard deviations above
the mean by the end of the day 1 period. The neighborhood
probabilities are high in both the HREF and RRFS for 1 and 2"+
amounts across these areas. Additionally, both the HREF and RRFS
show a defined area of probabilities exceeding the 3 hourly FFG
values in the 0000-1200 UTC Tuesday time frame as the potentially
organized convection presses east southeastward.

...Mid to Lower Mississippi Valley into the Ohio Valley...
A broad marginal risk area was maintained in association with height
falls pushing east northeastward from the Mid Mississippi Valley
through the Ohio Valley. Well defined large scale lift in an axis
of above average PW values, 1 to 1.5+ standard deviations above the
mean, will support the likelihood of widespread moderate to heavy
precipitation in an axis from northern AR, far southeast MO, far
southeast IL, western to central KY, much of IN and OH. At the
moment the convection across these areas may be fairly progressive.
This and very low relative soil moistures, much of the area in
moderate to severe drought, will keep the risk level at marginal
for the time being. While the HREF and RRFS neighborhood
probabilities are fairly high for 1 and 2"+ amounts day 1, the HREF
and RRFS probabilities for 3 hour rainfall exceeding FFG values
remains very low, reflecting the antecedent very dry conditions.

...Southwest...
The closed low off the Southern CA coast is expected to move
little during the upcoming day 1 period. The right entrance region
of the jet streak to the east of this closed low will push
eastward, but continue to support uvvs enhancement in the above
average PW axis, 1 to 3 standard deviations above the mean, that
will remain in place across Southern CA into the Southwest.
Additional scattered convection across these areas will support
localized heavy amounts and isolated runoff issues. No changes were
made to the previous marginal risk area.

Oravec


Day 2
Valid 12Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, NORTHERN ARKANSAS, NORTHEAST OKLAHOMA AND SOUTHEAST KANSAS...

The strengthening 850-700 mb moisture flux late day 1 over the
Southern Plains will remain anomalous day 2 as surface low
pressure continues to push eastward from the Southern Plains toward
the Lower Mississippi Valley. 850-700 mb moisture flux anomalies
are forecast to remain in the 2 to 3+ standard deviation above the
mean level. This will support the likelihood for the continuation
of the day 1 organized convection over the Southern Plains, pushing
eastward into the Lower Arkansas Valley and toward the Mid to Lower
MS Valley. There are differences with the track of the primary
surface low, resulting in north to south spread with respect to
where the max precip axis will be. WPC is favoring the more
southern qpf axes solutions, with the max axis depicted from far
eastern OK, northern OK/far southern MO into western TN. This is a
slight southward trend from previous forecasts, reflecting a
southward trend in qpf guidance. Changes to the previous slight and
25% areas were to follow the slight southward qpf axis trend,
pushing them approximately 40-60 miles farther to the south.

...Coastal Central California...
There is good model agreement with the nearly stationary closed
low off the Southern CA coast day 1 beginning to slowly move back
to the north on day 2 toward the Central CA coast. This slow north
movement will also allow for a northward expansion of the
anomalous PW values over Southern CA into coastal Central CA, with
values as high as 3-4 standard deviations above the mean. With good
model agreement on the closed low track day 2, there is also good
agreement on potential for areal average moderate precip totals,
with potential for locally heavier amount along the Central CA
coast. Isolated runoff issues are possible, especially over any burn scars.

Oravec


Day 3
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

The mid to upper level trof moving east from the Southern Plains
day 2 will amplify day 3 as it pushes into the Lower MS Valley.
Anomalous PW and 850-700 moisture flux values will stretch across a
large area from the Lower MS Valley, and into the TN & OH Valley,
Central Appalachians and the Mid-Atlantic. Model consensus is for a
broad region of moderate to heavy precip in this anomalous PW and
850-700 mb moisture flux axis. There is a typical amount of qpf
spread for a day 3 time period. WPC is leaning more toward the
multi model ensemble qpf mean axis/NBM axis to drive our qpf and
excessive rainfall axis. While a large portion of the day 3 QPF and
ERO axes are currently in moderate to severe drought, there may be
overlap in qpf areas from day 3 and day 1 over the TN and OH
Valley regions and overlap between the day 2 and day 3 qpf axes
across the Lower MS Valley into the TN Valley, which will likely
increase soil saturations and increase stream flows. The previous
slight risk area was trimmed on the western edge by approximately
75-100 miles across far southeast MO, southern IL and southern IN
to better fit the latest QPF.

...Central California...
The slow moving closed low approaching the central CA coast late
day 2 will continue to push slowly eastward day 3 and push inland
by early Thursday morning. Similar to the day 2 period, an axis of
anomalous PW values, 2 to 3 standard deviations above the mean,
will persist to the east northeast of the closed low across
Central CA. Scattered convection in this anomalous PW axis will
support locally heavy rains across Central CA and isolated runoff
issues, especially across burn scar regions. Only some small
changes made to the previous marginal risk area, trimming it
westward across western NV.

...Far southeast Arizona into New Mexico...
No changes of note made to the previous marginal risk area across
this region. Scattered convection possible, with localized heavy
rain and isolated runoff issues, especially in burn scar regions.

Oravec
$$
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FOUS30 KWBC 230825
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
425 AM EDT Tue Sep 23 2025

Day 1
Valid 12Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, FAR SOUTHEAST KANSAS, EASTERN OKLAHOMA, FAR NORTHEAST
TEXAS, ARKANSAS, WESTERN TENNESSEE, WESTERN KENTUCKY, AND SOUTHERN
ILLINOIS AND SOUTHERN INDIANA...

...Lower Arkansas Valley, Lower Mississippi Valley into the Lower
Ohio Valley...

The strengthening low level southerly flow/anomalous 850-700 mb
moisture flux that have supported organized convection over the
Central to Southern Plains early Tuesday will continue to support
the downstream push of this organized convection post 1200 UTC,
with these anomalous 850-700 mb moisture flux values of 2-3+
standard deviations above the mean moving from the eastern sections
of the Southern Plains into the Lower AR Valley, Lower MS, TN and
OH Valleys. There continues to be some north south spread in the
models with respect to the position of the max precip axis.
Generally, the non-CAMs are farther north and the CAMs farther
south. WPC continues to support the farther south qpf solutions,
with our day 1 risk areas drawn toward them. Overall, not a lot of
changes to the previous slight risk areas. We did extend the slight
risk farther east into the Lower OH Valley where there is expected
to be overlap of day 1 heavy precip with observed precip over the
past 24 hours. We also extended the slight risk area farther south
into northeast TX where several of the new 0000 UTC hi-res runs and subsequently the new HREF mean show heavy precip. Otherwise, the
slight and 25% areas fit well with where the HREF and RRFS
neighborhood probabilities are high day 1 for 2" and 3+ amounts.

...Coastal Central California...
There continues to be good model agreement with the nearly
stationary closed low off the Southern CA coast beginning to
slowly move back to the north on day 1 toward the Central CA
coast. This slow north movement will also allow for a northward
expansion of the anomalous PW values over Southern CA into coastal
Central CA, with values as high as 3-4 standard deviations above
the mean. With good model agreement on the closed low track day 1,
there is also good agreement on potential for areal average
moderate precip totals, with potential for locally heavier amount
along the Central CA coast. Isolated runoff issues are possible,
especially over any burn scars.

Oravec


Day 2
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

Anomalous PW and 850-700 moisture flux values will stretch across a
large area from the Lower MS Valley, and into the TN & OH Valleys,
Central Appalachians and the Mid-Atlantic, ahead of the amplifying
longwave trof stretching from the Great Lakes, southward into the
Lower MS Valley. There still is a fair amount of qpf spread with
the max axis day 2. WPC is leaning more toward the multi model
ensemble qpf mean/NBM to drive our qpf and excessive rainfall
axes. This will support a widespread axis of moderate to heavy
precip amounts from eastern TX into the Lower MS Valley, TN and OH
Valleys. While a large portion of the day 2 QPF and ERO axes are
currently in moderate to severe drought, there may be overlap in
qpf areas from day 2 and what has fallen over the past 24 hours
from eastern TN into central to eastern KY, and the Upper OH Valley
region. The previous slight risk was narrowed to better fit this
potential overlap areas. The marginal risk was also trimmed
significantly from southern L.P. of MI, IL, southeast MO and AR to
better fit the latest qpf update.

...Central California...
The slow moving closed low approaching the central CA coast late
day 1 will continue to push slowly eastward day 2 and push inland
by early Thursday morning. Similar to the day 1 period, an axis of
anomalous PW values, 2 to 3 standard deviations above the mean,
will persist to the east northeast of the closed low across Central
CA. Scattered convection in this anomalous PW axis will support
locally heavy rains across Central CA and isolated runoff issues,
especially across burn scar regions.

...Far southeast Arizona into New Mexico...
No changes made to the previous marginal risk area across this
region. Scattered convection possible, with localized heavy rain
and isolated runoff issues, especially in burn scar regions.

Oravec


Day 3
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

The slow moving closed low moving inland into Central CA day 2 will
drop back to the south southeast toward Southern CA day 3. This
system will continue to have an area of anomalous PW values in the
vicinity of the upper center across Central CA into the Great
Basin. This closed low will also begin to tap anomalous PW values
over northwestern Mexico, transporting them into southeast Arizona
day 3. Model consensus is for a max precip area over Southeast
Arizona and far southwest New Mexico. The previous slight risk
across this area was only modified slightly, expanding it slightly
to the north and east to cover the model max qpf spread. Only some
minor changes to the marginal risk to the northwest of this across
northern AZ, southern NV, far southwest UT and into the central
Sierra. Locally heavy rains and isolated runoff issues possible
across these areas, especially over burn scars.

...Southern to Central Appalachians...
There will continue to be a broad axis of above average PW values
pushing eastward day 3 ahead of the elongated upper trof
stretching from the Great Lakes into the OH and TN Valleys. There
is a lot of qpf differences in this high PW axis, leading to low
confidence in where to put risk areas. Much of the eastern U.S. is
in drought conditions with low relative soil moisture levels. One
exception is over portions of the Southern to Central Appalachians
from eastern TN/far western NC/far southwest VA and eastern WV.
Kept the day 3 marginal confined to these areas and removed the
broader marginal from the previous issuance that extended north and
east into the Mid-Atlantic and southwestward to the Gulf Coast.

Oravec
$$
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FOUS30 KWBC 240831
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
431 AM EDT Wed Sep 24 2025

Day 1
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

...Southern Plains to the Central and Southern Appalachians...

Overall, no large-scale changes to the previous outlook areas,
maintaining a broad Marginal Risk that extends from portions of
central and southern Texas to the southern and central
Appalachians, with an embedded Slight Risk centered over parts of
the Ohio and Tennessee valleys.

Composite radar this morning shows widespread showers and storms
extending from the Ohio Valley back into the southern Plains. The
overnight CAMs indicate that ongoing storms along the far eastern Oklahoma-Texas border into southern Arkansas will remain organized
into the late morning as the drift slowly south, with training
storms likely to produce heavy amounts across portions of
northeastern Texas and northwestern Louisiana. Supported by
shortwave energy moving through the base of a broader-scale
positively-tilted upper trough and PWs at or above 2 inches, HREF
probabilities indicate locally heavy amounts exceeding 3 inches are
likely. However, dry soil conditions, reflected by high FFGs, are
expected to limit the threat for widespread flooding concerns.

As energy continues to move through the base of the upper trough,
an area of low pressure is expected to become better organized and
track northeast through the Ohio Valley beginning later this
afternoon and continuing into the overnight. Deep southwesterly
flow ahead of the wave will support increasing moisture, with PW
anomalies increasing to over 2 std dev above normal per the GFS.
Given the ongoing rains and relatively wetter soil conditions
(lower FFGs), a Slight Risk extending from far northern Alabama to
far southern Ohio and western West Virginia was maintained. HREF
probabilities indicate that amounts of 1-2 inches will be common,
with locally heavier amounts over 3 inches possible within the
Slight Risk area.

In the wake of the low, showers and storms producing heavier rates
are expected along the trailing front as it sinks south through
the lower Mississippi Valley and along the upper Texas coast back
into South Texas. Here too, the HREF is indicating locally heavy
amounts over 3 inches are likely. But similar to areas to the
north, higher FFGs suggest flooding issues will be mostly contained
to vulnerable areas, including urbanized centers.

...Northeast...

The general consensus of the CAMs shows an area of showers and
storms moving northeast well in advance of the system over the Ohio
Valley. Supported by deepening moisture along a slow-moving
boundary and increasing mid-to-upper level forcing, showers and
storms will advance northeast across Pennsylvania, with repeating
storms potentially resulting in locally heavy amounts from
northeastern Pennsylvania into the lower Hudson Valley/NYC area. A
A Marginal Risk was maintained for areas where the HREF shows
higher probabilities for amounts over 2 inches and where FFGs are
relatively lower.

...Southeastern Lower Michigan...

An upper low closing off this morning is expected to remain
centered over Lower Michigan into Thursday morning. Showers and
storms are likely to develop east of the center, with relatively
deeper moisture wrapping into the system raising the potential for
locally heavy rainfall rates. A small Marginal Risk was
introduced, highlighting the area where the HREF shows high
probabilities for accumulations exceeding 2 inches.

...Central California...

A slow-moving upper low currently offshore will drift north and
begin moving inland Thursday morning. With anomalous moisture
remaining in place (2.5-3 std dev above normal), locally heavy
amounts will remain possible. Reflecting the high HREF
probabilities for amounts over an inch, a Marginal Risk was
maintained along the central California Coast from the Monterey
Bay south and along the adjacent mountains.

Pereira


Day 2
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

...Southwest to Sierra Nevada...

After moving inland early Thursday, the closed low over central
California is forecast to drop south into southern California by
early Friday. With ample moisture remaining in place (2-3 std
dev above normal) near and east of the upper center, locally heavy
amounts are possible from the Sierra Nevada east into southern
Nevada and southwestern Utah.

As the center drops south, increasing southerly flow east of the
low will draw deeper moisture up from Mexico, fueling widespread
shower and thunderstorm coverage, especially across southeastern
and central Arizona into southwestern New Mexico. A Slight Risk
was maintained across this area where PWs are forecast to increase
to 1-2 standard deviations above normal by the afternoon.

...Northeast...

Unsettled weather developing Day 1 is forecast to continue into
Thursday as showers and storms continue to develop ahead of the
system lifting out of the Ohio Valley into the Northeast.
Strengthening southwesterly flow along the Mid Atlantic coast into
the Northeast will support deepening moisture (PWs increasing to ~2
inches) and an increasing threat for heavy rainfall rates. A
Marginal Risk was maintained from northern New Jersey into southern
New England, where HREF probabilities indicate that localized
amounts over 3 inches are possible late Thursday morning into the
afternoon.

...Southern Appalachians...

The consensus of the latest guidance indicates that showers and
storms developing along and ahead of the cold front trailing the
low moving through the Northeast will be generally progressive.
With widespread heavy amounts not expected and FFGs high, the
previous Marginal Risk was removed from much of the Mid Atlantic.
However, some models do show the potential for training storms to
produce some localized heavy amounts (2+ inches) across parts of
the southern Appalachians, where a small Marginal Risk was
maintained.

Pereira


Day 3
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND SOUTHWEST NEW MEXICO...

...Southwest...

A second day of numerous showers and storms is expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico. The upper low setting into southern
California the previous period is expected to move little this day,
remaining centered near the California/Mexico border. This will
help to maintain anomalous moisture across the region, fueling
widespread shower and thunderstorm coverage during the afternoon
and evening hours. A Slight Risk, with a footprint similar to the
Day 2 area, was maintained for Day 3 across parts of Arizona and
New Mexico.

...Southeast...

A boundary will remain in place across the Southeast as an upper
trough evolves into a closed low that is forecast to linger beyond
the period. Moisture and energy lifting ahead of the closing system
will support periods of shower and storms. While the guidance at
this point is not signaling any widespread heavy amounts, the
pattern does lend itself to at least the threat for locally heavy
amounts, which may raise at least isolated flooding concerns.

Pereira
$$
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FOUS30 KWBC 250744
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
344 AM EDT Thu Sep 25 2025

Day 1
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

...Southwest to Sierra Nevada...
A cold low near the central California coast is forecast to drop
southeast into southern California by early Friday. With cold air
aloft overlying sufficient moisture near and east of the upper
center, locally heavy amounts are possible from the Sierra Nevada
east into southern Nevada and southwestern Utah.

Ahead of the system, increasing southerly flow will draw deeper
moisture into the Southwest from the Gulf of CA, fueling
widespread shower and thunderstorm coverage, especially across
southeastern and central Arizona into southwestern New Mexico. ML
CAPE should rise into the 1000-2000 J/kg range. A Slight Risk was
maintained across this area where cold air aloft interacts with
monsoon-like moisture, with precipitable water values as high as
1.25-1.5". Hourly rain amounts to 2" are possible where cells merge
and/or train.

...Northeast/Upper Ohio Valley...
Unsettled weather at the present time is forecast to continue into
Thursday as showers and storms stream east across the Upper Ohio
Valley, WV, and southwest PA ahead of a shortwave aloft and surface
frontal wave. While there may be a gap in heavy rainfall between
this region and points farther east, chose to connect the areas
and significantly broaden the inherited Marginal Risk.
Strengthening southwesterly flow along the Mid Atlantic coast into
the Northeast will support deepening moisture (PWs increasing to
~2") and ML CAPE surpasses 1000 J/kg. Hourly amounts to 2.5" are
possible in this region with local totals to 4", but coverage of
such amounts should be sparse enough for a Marginal Risk to still apply.

...Southern Appalachians into parts of the Gulf Coast...
Amplifying mid-upper trough digging into the northwest and north-
central Gulf will slow the south and east progression of the
surface cold front and pre-frontal buoyant airmass. ML CAPE values
should rise to 1000 J/kg or so across the southernmost
Appalachians while areas of the Gulf Coast see 2000-3000 J/kg of ML
CAPE. With precipitable water values at or above 2", hourly rain
amounts to 2.5" with local totals to 4" are possible wherever short
periods of training or cell mergers are able to occur. Activity
currently across South TX should survive past 12z, so looped the
Marginal Risk to encompass this area. At the present time, any
flash flood issues are expected to be isolated to widely scattered.

Roth


Day 2
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND SOUTHWEST NEW MEXICO...

...Southwest...
Numerous showers and thunderstorms are expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico. An upper low should slow to a crawl
across southeast California. Precipitable water values should
remain as high as 1.25-1.5" in spots, but the guidance shows more
potential on the ML CAPE front when compared to Thursday, with
values of 2000-3000 J/kg possible as available moisture interacts
with the cold pool aloft. Widespread shower and thunderstorm
coverage is expected, particularly during the afternoon and evening
hours. A Slight Risk, with a footprint similar to the Day 2 area,
was maintained for Day 3 across parts of Arizona and New Mexico,
but it could be higher end Slight Risk. Hourly rain amounts to 2"
are possible where cells merge and/or train.

...Southeast...
A boundary will remain in place as a cold low forms near the base
of an upper level trough, a feature that lingers for a while near
the Southern Appalachians. Moisture and instability lifting ahead
of the closing system will support periods of showers and storms.
Precipitable water values of up to 2" with ML CAPE to 1000 J/kg
across the Piedmont and 2000-3000 J/kg in coastal areas are
expected, which could yield hourly rain amounts to 2.5" and local
totals to 4".

Roth


Day 3
Valid 12Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS & NEW MEXICO...

Southwest/Southern Rockies...
An upper low remains fixed across the Lower Colorado River while
Gulf Moisture streams into the TX Big Bend and New Mexico, moving
up the Rio Grande. Precipitable water values of 1.25-1.5" are
forecast, which when combined with up to 1000 J/kg of ML CAPE could
yield hourly amounts to 2.5" and local totals to 4" where cells
train and/or merge. Believe the risk level from continuity (Slight)
conveys the risk appropriately at this time for portions of far
west TX and NM. Closer to the upper level center across the
Southwest, slow-moving convection is possible under the cold pool
aloft. Based on the decline of the 1000-500 hPa thickness across UT
towards 5670 meters, limited the northern extent of the Marginal
Risk to southern UT which is about the northern extent of the 0.75" precipitable water value, which was coordinated with the SLC/Salt
Lake City forecast office.

Carolinas/Southern Mid-Atlantic States...
Divergence aloft around the eastern periphery of a cold low near
the Southern Appalachians maintains precipitable water values of
2"+ near the coast, which should also see the greatest instability,
up to 1000 J/kg. The guidance shows a bit of dispersion here in placement/northeast movement of the heavy rain area with the GFS
and NAM in their usual camps (fast and slow, respectively). Hourly
rain amounts to 2.5" and local totals to 4" are expected, similar
to previous days. Forecast uncertainty, as much as anything else,
maintained the risk level as a Marginal. Should the guidance
converge, areas of risk overlap between Friday and Saturday across
portions of the coastal plain of the Carolinas could see an upgrade
to a Slight Risk at some point as we get closer to Saturday.

Roth
$$
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FOUS30 KWBC 260808
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
408 AM EDT Fri Sep 26 2025

Day 1
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHWEST & IN THE VICINITY OF THE CAROLINAS...

...Southwest...
Numerous showers and thunderstorms are expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico, which should occur primarily during the
afternoon and evening hours. An upper low should slow to a crawl
across southeast California. Precipitable water values should
remain as high as 1.25-1.5" in spots. ML CAPE values of 2000-3000
J/kg are possible as available moisture interacts with the cold
pool aloft. A Slight Risk was maintained across parts of Arizona
and New Mexico, but it could be higher end Slight Risk. Hourly rain
amounts to 2" with local totals to 4" are possible where cells
merge and/or train.


...Southeast...
A boundary will remain in place as a cold low forms near the base
of an upper level trough, a feature that lingers for a while near
the Southern Appalachians. Farther inland across the Piedmont, some
degree of upslope flow should bring some of the higher moisture
back in from the southeast. Moisture and instability lifting ahead
of the closing system will support periods of showers and storms.
Precipitable water values of up to 2" with MU CAPE of 1000+ J/kg
across the Piedmont and 2000-3000 J/kg in coastal areas are
expected, which could yield hourly rain amounts to 2.5" and local
totals to 4". As the 00z HREF and 18z REFS had their strongest
signal for 3"+ and 5"+ across far southwest VA and the western
Carolinas, a Slight Risk was added in this update, which was
coordinated with the local offices. For the time being, a Slight
Risk was left out across the coastal plain of the Carolinas as
recent dryness could make a higher incidence of flash flooding
harder to come by, which was coordinated with the coastal Carolina
offices.

Roth


Day 2
Valid 12Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025


...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS & NEW MEXICO...

...Southwest/Southern Rockies...
An upper low remains fixed across the Lower Colorado River while
Gulf Moisture streams into the TX Big Bend and New Mexico, moving
up the Rio Grande. Precipitable water values of 1.25-1.5" are
forecast, which when combined with 1000+ J/kg of ML CAPE could
yield hourly amounts to 2.5" and local totals to 4" where cells
train and/or merge. Believe the risk level from continuity (Slight)
conveys the risk appropriately at this time for portions of far
west TX and NM. Closer to the upper level center across the
Southwest, slow-moving convection is possible under the cold pool
aloft, with ML CAPE of 1000-2000 J/kg of instability and
precipitable water values in the Lower Desert of 1-1.25" expected.
Based on the decline of the 1000-500 hPa thickness across UT
towards 5670 meters, limited the northern extent of the Marginal
Risk to southern UT which is about the northern extent of the 0.75" precipitable water value.


...Carolinas/Southern Mid-Atlantic States...
Divergence aloft around the eastern periphery of a cold low near
the Southern Appalachians and what is now a tropical disturbance
moving through the Bahamas as a possible tropical cyclone on
Saturday team up to maintain precipitable water values of up to
2.25" across the coastal plain, which should also see the greatest
instability, 1000-2000 J/kg. The Piedmont should see times when the
MU CAPE rises above 500 J/kg. This is a PRE-like set up for the
region, so the heavy rainfall potential has a higher upside than
usual. There has been some convergence in the model guidance QPF-
wise, and both the 00z HREF and 18z REFS had a cohesive and
agreeable enough heavy rain threat of 3"+ for a new Slight Risk
area from roughly Richmond VA south on both sides of the fall line
into eastern SC. Hourly rain amounts to 3" and local totals to 6"
are possible, which is potentially problematic anywhere within the
Slight Risk area. A higher risk level can't be ruled out in future
updates.

Roth



Day 3
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS, NEW MEXICO, & THE CAROLINAS...

Southwest/Southern Rockies...
The combination of an upper low moving to near the Four Corners, a
kicker upper level trough moving into CA, and moisture feed from
the Gulf into NM persist into Sunday. Precipitable water values
remain above 1" locally in the Desert Southwest and 1-1.25" in the
Southern High Plains. Pockets of 1000+ J/kg of ML/MU CAPE are
forecast to develop and/or persist. A Slight Risk still appears
reasonable across portions of far west TX and NM, with a broader
Marginal Risk surrounding that. The guidance appears to be trending
somewhat drier across the Great Basin, so limited the northern
extent of the Marginal Risk area when compared to continuity.


Florida northward into the Southern Mid-Atlantic States...
A system now considered a tropical disturbance over Hispaniola
should lie somewhere north of the Bahamas and east of Florida as a
possible tropical or hybrid cyclone on Sunday. The upper level
environment doesn't look kind for whatever emerges, and there are
two scenarios -- a more convective system that remains offshore
during the medium range period or a more sheared system that
attempts to occlude when it approaches landfall early next week.
The guidance is not ideal in differentiating which is correct
during these scenarios, historically.

Regardless, moisture will not be a problem regionally --
precipitable water values locally 2"+. Coastal areas will see
1000+ J/kg of ML CAPE while 250+ J/kg of MU CAPE invades portions
of VA. The guidance has slowed down the approach of the tropical
low since yesterday, but the other players in the flow pattern
remain -- the upper low near the southern Appalachians/southern
Cumberland Plateau and the front near the East Coast. A PRE- like
set up appears to be in the cards, with moisture streaming into the
front from the south. The best signal for heavy rainfall on Sunday
into early Monday appears to be in the vicinity of Myrtle Beach,
and considering previous days of rain, thought a new Slight Risk in
that area would be prudent. In theory, hourly rain amounts to 3"
should be possible, which would be most problematic should
thunderstorms merge or train.

Roth
$$
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FOUS30 KWBC 270831
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
431 AM EDT Sat Sep 27 2025

Day 1
Valid 12Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHWEST AND MID-ATLANTIC...

Southwest/Southern Rockies/High Plains

A closed upper low over the Southwest will generate scattered
thunderstorm activity across the region and into parts of the
Southern High Plains/Rockies beginning this afternoon. Anomalous
moisture (1in+ PWAT/2-3 StD) within a bouyant environment 1000+
MUCAPE should yield modest rain rates of over an inch/hr,
especially over favorable upslope terrain. Burn Scars and slot
canyons will be among the most susceptible to flash flooding.

Mid-Atlantic/Southeast

An upper trough will continue supplying ample moisture (1.5-2in+
PWAT) and sufficient instability (500 J/Kg+) to the Mid-
Atlantic/Southeast Coastline today. Storms should develop within
the warm sector of a stationary front draped across the Southern
Appalachians and Mid-Atlantic Coast. The heaviest rainfall (1-2
in/hr rates) should focus around the aforementioned front where
favorable right entrance region dynamics will likely develop and
prolong storms during peak heating hours.


Kebede

Day 2
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
FAR WEST TEXAS, NEW MEXICO AND SOUTHWESTERN COLORADO...

Southwest/Four Corners/Southern High Plains/Rockies

The upper low in the Southwest is expected to open as it lifts
into the Rockies on Sunday. The threat for excessive rainfall thus
expands a bit around the trough as the fetch of moisture from the
previous day rotates around the low and into parts of the Great
Basin and Four Corners. Some elevated instability 500 J/Kg+ MUCAPE
could generate 0.5-1.5 in/hr rates, especially over parts of New
Mexico, where a slight risk is in effect. Antecedent rainfall from
Saturday should lower FFGs, making soils more vulnerable to flash
flooding. Slot canyons, dry washes and upslope areas will likely be
the most susceptible to runoff.

Southeast

Guidance continues to trend farther away from the Southeast Coast
with the axis of substantial QPF associated with a tropical
cyclone moving through the Bahamas at the beginning of the day 2
period (Sunday morning). Given the uncertainty of the system's
track, it's difficult to say with any confidence if/where the most
impactful rainfall will occur, thus a broad marginal is in place
from the Outer Banks down to Miami for now.


Kebede

Day 3
Valid 12Z Mon Sep 29 2025 - 12Z Tue Sep 30 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHEAST AND MID-ATLANTIC...

Southeast/Mid-Atlantic

Tropical moisture arrives along the Southeast/Mid-Atlantic Coast
on Monday ahead of the associated cyclone, which is currently
forecast to be east of Georgia by Tuesday morning. Current
deterministic guidance has between 2-4 inches of rainfall occurring
along the Carolina Coast with isolated higher amounts. Models are
trending away from the coast with the cyclone's track, which is
reflected in a decreasing QPF trend with this cycle as well.

Northern California/Southwest Oregon

A deep East Pacific trough will bring broad diffluent flow aloft
over the Northwest Coast beginning Monday morning. Scattered
showers and thunderstorms may develop along the leading edge of a
surface front, where the presence of weak instability (350 J/Kg
MUCAPE) and modest moisture (~1 in. PWAT) could produce localized
flash flooding along the northern California/southwest Oregon
Coasts and inland into the Southern Cascades and northern Sierra.

Kebede
$$
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FOUS30 KWBC 280829
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
429 AM EDT Sun Sep 28 2025

Day 1
Valid 01Z Sun Sep 28 2025 - 12Z Sun Sep 28 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS MUCH OF NEW
MEXICO AND PORTIONS OF FAR WESTERN TEXAS/SOUTHERN COLORADO...

...Four Corners/Southwest...
An upper trough centered over the Southwest will continue
directing mid-level vortices northward through the Four Corners
region today. Moisture from Tropical Cyclone Narda in the East
Pacific will continue surging north into the Four Corners, where
scattered showers and thunderstorms are likely to proliferate throughout
the day. PWATs between 1-1.5 inches within the right entrance
region of the upper jet and modest instability around 500-1000+
J/Kg (MLCAPE) could yield rain rates between 0.5-1 in./hr.,
especially where the slight risk is currently drawn. Burn scars,
scars slot canyons and upslope areas within the risk areas are
especially vulnerable to flash flooding.

HREF's neighborhood exceedance probabilities of 2 in. in 24 hours
are between 25-50% while EAS probabilities of exceeding 0.5 in.
hover around 20-40% within the depicted slight risk area.


...Southeast...
An upper trough will pivot eastward over the Southeast while
moisture from T.C. Nine continues surging northward toward the
Southeast Coast. Current guidance keeps the axis of heaviest QPF
offshore, but enough moisture may propagate far enough north and
west to interact with a surface front draped along the coast and
produce localized excessive rainfall. HREF EAS exceedance
probabilities of 1 inch in 24 hours are between 5-15% along much
of the Carolina Coast today, which supports the marginal risk area
depicted.

Kebede

Day 2
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
CAROLINA COAST...

...Southeast...
Guidance continue to depict T.C. Nine propagating north toward the
Southeast Coast on Monday, while a surface front draped along the
coast acts as the focus for heavy rainfall. QPF has trended
downward given slowing trends in the track of T.C. Nine on Monday.
The GFS suite in particular diverges most from the Canadian and
Euro suites when depicting the system's slower forward motion.
Despite this, enough moisture should work its way into the coast
and interact with the surface front to generate scattered thunderstorms. There'll be enough moisture (1.5-2.5in PWATs) and instability
(1000+ J/KG MUCAPE) present to support rainfall rates in excess of
1 in./hr..

...Northern California/Great Basin/Southern Cascades...
An upper low centered over the East Pacific will send mid-level
vortices into the West Coast on Monday. Pacific moisture may
collide with the remnant tropical moisture from Narda to produce
heavy rainfall from northern California into the Great Basin.
Synoptic forcing provided by a strong surface cold front should
focus PWATs in the range of 0.75-1.25 in. to produce quarter inch
rain rates along the immediate coast. More robust instability over
the Great Basin should yield higher rain rates between 0.5-1
in./hr. in some areas. Upslope enhancement may generate higher
totals in parts of the terrain.

Kebede

Day 3
Valid 12Z Mon Sep 29 2025 - 12Z Tue Sep 30 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
CAROLINA COAST...

...Southeast...
The inherited marginal and slight risk areas along the Southeast
Coast were downsized based on trends in the guidance suggesting
T.C. Nine's hard turn out to sea on Tuesday. Despite the resulting
smaller QPF footprint than previous cycles, the flash flood risk
remains. Instability will be negligible (less than 500 J/Kg
MUCAPE), which supports the possibility that the flood threat will be
due to runoff over saturated soils from Sunday and Monday's
rainfall. Exceedance probabilities of over 2 inches is over 10% in
the 00z ECENS/CMCE, while below 10% in the GEFS along the
immediate Carolina Coast.

Kebede
$$
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FOUS30 KWBC 290830
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
430 AM EDT Mon Sep 29 2025

Day 1
Valid 01Z Mon Sep 29 2025 - 12Z Mon Sep 29 2025

...THERE ARE MARGINAL RISKS OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTHERN CALIFORNIA, SOUTHWESTERN OREGON, THE GREAT BASIN, SOUTH-
CENTRAL NEW MEXICO AND THE SOUTHEAST...

...Carolinas...
Moisture from tropical storm Imelda is expected to continue
streaming into the Southeast Coast today. A surface front draped
off the coast should provide forcing for thunderstorm development
beginning this morning. Convective bands may work their way into a
moisture rich environment in the Carolinas, where PWATs will be
between 1.5-2.25in.. MUCAPE between 250-500 J/Kg will spread
inland throughout the day, but the greatest convective potential
will be within the bands that propagate inland through North
Carolina this morning and afternoon. Neighborhood probabilities of
exceeding 2 inches of rainfall in 24 hours are between 15-30% over
parts of western and central North Carolina today.

Despite the presence of deep tropical moisture, much of the
convection and heaviest rainfall associated with Imelda should stay
offshore closer to Imelda and the draped front.

...Northern California/Great Basin...
A deep upper low centered over the Gulf of Alaska will send waves
of low pressure into the West Coast over the next couple of days.
A strong cold front may bring heavy rainfall to portions of
Northern California up into southern Oregon and the Great Basin
today. A weak instability gradient will develop ahead of the front
this afternoon and during peak heating. The 00z HREF suggest up to
0.25in./hr. rates across the coastal ranges, southern Cascades and
northern Sierra, with potential for upslope enhancement across
windward facing slopes.

EAS 24 hour 1 inch exceedance probabilities are over 45% along the
coast and southern Cascades, while a more modest 5-15% chance
remains over the Great Basin. There's a steep drop off in
probabilities once you get into the 2 inch exceedance range.

...South-central New Mexico...
There continues to be a signal for heavy rainfall over much of the
Sacramento Mountains, where instability (500-1000 J/Kg MLCAPE)
could support thunderstorm development and propagation into the
mountains early this evening. Much of the state has already
received over a half inch of rainfall in the past 24 hours with
pockets of 2 inch amounts present including within the Sacramento
Mountains. This may contribute to susceptibility of soils to runoff
from additional rain. Burn Scars such as the Ft. Stanton Piles
prescribed burn area are especially susceptible to flash flooding.

Kebede


Day 2
Valid 12Z Mon Sep 29 2025 - 12Z Tue Sep 30 2025

...THERE'S A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE GREAT BASIN AND NORTHERN ROCKIES...

The marginal risk area inherited from the previous cycle was mostly
maintained with an expansion south into central Utah due to trends
in the guidance. The cold front responsible for heavy rainfall
potential in northern California on Monday will propagate through
the Great Basin and Northern Rockies on Tuesday, focusing
additional instability and moisture along its convergence zone.
Ensemble exceedance probabilities of 0.5 inches in 24 hours are
between 5-25% over parts of northeastern Nevada, northern Utah,
southeastern Idaho and western Wyoming. The progressive nature of
the front should mitigate flash flooding concerns.

Kebede


Day 3
Valid 12Z Tue Sep 30 2025 - 12Z Wed Oct 01 2025

...THERE'S A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE OLYMPIC PENINSULA...

A shortwave propagating through the southern periphery of the Gulf
of Alaska low will phase with it and move just off of the British
Columbia Coast by Wednesday. This new system will send a cold
front into the Pacific Northwest. The proximity of the upper low
and associated vorticity lobes should destabilize the environment
(100-300 J/Kg MUCAPE) enough to support isolated thunderstorm
activity. Favorable RER dynamics and mid-level moisture
advection should support efficient rain rates especially over the
Olympic Mountains. ECENS 24 hour exceedance probabilities of 2
inches is between 20-40% for much of the area.

Kebede
$$
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FOUS30 KWBC 300816
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
416 AM EDT Tue Sep 30 2025

Day 1
Valid 01Z Tue Sep 30 2025 - 12Z Tue Sep 30 2025

...THERE'S A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE OLYMPIC MOUNTAINS, GREAT BASIN AND NORTHERN ROCKIES...

...Great Basin/Northern Rockies...
A deep upper low off the British Columbia Coast will send
shortwave energy through the Northwest today. A progressive cold
front will focus showers and thunderstorms over portions of the
Great Basin from northeast Nevada to western Montana/northern
Idaho. MUCAPE values between 100-500J/Kg and PWATs of 0.5-1in.
could produce excessive rainfall through this afternoon. This will
be especially true over portions of eastern Nevada into northern
Utah where 24 hour 1 inch exceedance probabilities are between 20-45%.

...Olympics...
The occluded parent low will direct anomalous Pacific moisture at
the Olympic coast beginning this afternoon. Some weak instability
(<200J/Kg MUCAPE) and PWAT's around 1 inch could produce some cells
capable of generating efficient rain rates, especially within the
windward side of the Olympics. IVT values between 500-700Kg/ms
support the excessive rainfall threat with isolated instances of
flash flooding.

Kebede


Day 2
Valid 12Z Tue Sep 30 2025 - 12Z Wed Oct 01 2025

...THERE'S A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE OLYMPIC MOUNTAINS...

The excessive rainfall threat over the Olympics bleeds into
Wednesday as the upper low arrives off the coast of the Pacific
Northwest. A jetstreak aloft with MUCAPE around 150J/Kg Wednesday
morning could support some weak convection into the Olympics.
Unlike on day 1, maximum IVT values will remain offshore with 1
inch PWATs arriving early Thursday morning. Canadian and Euro
ensemble 2 inch exceedance probabilities are between 40-60% while
the GEFS 1 inch probabilities are around an inch.

Kebede


Day 3
Valid 12Z Wed Oct 01 2025 - 12Z Thu Oct 02 2025

...THERE'S A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE GREAT BASIN AND EASTERN FLORIDA...

...Great Basin...
The upper low is expected to dig into the West Coast on Thursday
directing diffluent flow and left exit region jet dynamics into the
Great Basin. Weak instability (100-200J/Kg MUCAPE) along a
developing cold front could generate thunderstorms capable of
producing some isolated flash flooding, especially over parts of
the Great Basin that received rainfall on Tuesday.

...Eastern Florida...
An upper trough in the Southeast will direct embedded vorticity
into the Florida peninsula on Thursday. An upper ridge centered
over the West Atlantic will advect tropical moisture (PWATs
between 1.5-2in.) into eastern Florida, where it'll interact with
an inverted trough along the coast. Multiple rounds of short fused
convection will proliferate from the central Gulf across the
Florida Peninsula throughout the day with onshore flow into eastern
Florida producing isolated instances of flash flooding.
Probabilities of 24 hour qpf exceeding 1 inch is between 15-30%
across eastern Florida. Urban areas are especially susceptible to
flash flooding.

Kebede
$$
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FOUS30 KWBC 010833
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
433 AM EDT Wed Oct 1 2025

Day 1
Valid 12Z Wed Oct 01 2025 - 12Z Thu Oct 02 2025

...THERE'S A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE OLYMPIC PENINSULA AND EASTERN FLORIDA...

...Olympic Peninsula...
A deep upper low centered off of the British Columbia Coast will
direct embedded ripples of vorticity into the Pacific Northwest
today. A strong 60-100 kts RER jet with associated 100-200 J/Kg
MUCAPE and 200-400 Kg/ms IVT out of the southwest should be enough
to generate scattered thunderstorm activity across the region
today. These favorable dynamics paired with PWATs between 0.65-0.90
should produce efficient rain rates throughout the day, especially
along the windward side of the Olympics, where upslope enhancement
may occur.

...Eastern Florida...
A positively tilted trough will swing through the Southeast today.
CAA over warm Gulf/Atlantic waters should generate convection along
a surface convergence zone over the Florida Coast today. MUCAPE
between 500-1000 J/Kg within a moist environment (1.75-2.25 in.
PWATs) should produce scattered thunderstorms with efficient rain
rates. Moist easterly flow over the inverted coastal surface trough
may generate some backbuilding storms this afternoon/evening. HREF
5" neighborhood exceedance probabilities are between 20-30% across
the entire risk area, so there's potential for overperformance of
rainfall. Urban areas are of particular concern to flash flooding.

Kebede


Day 2
Valid 12Z Thu Oct 02 2025 - 12Z Fri Oct 03 2025

...THERE'S A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE OLYMPIC PENINSULA, THE SIERRA, THE GREAT BASIN AND EASTERN FLORIDA...

...Olympic Mountains...
The excessive rainfall threat spills over into Thursday across the
Olympics as the upper low begins to dig down into the West Coast.
100-200 J/Kg MUCAPE and 0.75-1" PWATs should sustain the potential
for excessive rainfall, particularly earlier on in the period
(12-18z) before the trough pushes farther east into the interior
and high pressure builds over the Olympic Peninsula. CMCE 1"
exceedance probabilities are around 15-35% within the marginal risk area.

...Great Basin/Sierra...
Strong diffluence associated with the digging upper trough will
spread throughout the interior West on Thursday. An 80-100 kts RER
jet with a 100 J/Kg MUCAPE should support convection with PWATs
between 0.75-1", which will be 3-4 stndv above average. This will
provide enough moisture to produce high enough rain rates to
overtake flash flood guidance, which is below 1".

...Eastern Florida...
Shortwave vortices within a mean upper trough will propagate south
through the Florida Peninsula on Thursday. Sufficient instability
(500-1000 J/Kg MUCAPE) and moisture (2"+ PWATs) associated with
Imelda may produce excessive rainfall along the immediate coast
early on in the day. The latest qpf trend is decreasing, partly
because the heavy rainfall threat is split between two days (00z
Wednesday--15z Thursday), but urban areas continue to be
susceptible to runoff.

Kebede


Day 3
Valid 12Z Fri Oct 03 2025 - 12Z Sat Oct 04 2025

...THERE'S A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
EASTERN FLORIDA...

...Eastern Florida...
Continued troughing in the Southeast will promote more unsettled
weather across Florida on Friday. Easterly flow will continue
advecting rich tropical moisture (2-2.25" PWATs) from Imelda into
the Peninsula with plenty of instability (500-1000 J/Kg MUCAPE) to
generate scattered thunderstorms. 2" ensemble exceedance
probabilities are between 5-15%, which supports the inherited
marginal risk area. Again, the greatest threat for flash flooding
is in urbanized areas.

Kebede
$$
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FOUS30 KWBC 020828
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
428 AM EDT Thu Oct 2 2025

Day 1
Valid 12Z Thu Oct 02 2025 - 12Z Fri Oct 03 2025

...THERE'S A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SIERRA, GREAT BASIN AND EASTERN FLORIDA...

...Sierra/Great Basin...
An upper low will dig into the West Coast while sending streams of
vorticity into the Sierra Nevada, Great Basin and Northern
Rockies. Diffluence will spread across the aforementioned areas
throughout the day on Friday. At the surface, a low pressure system
will propagate across the interior West, while anomalous moisture
(3-4 stndv PWATs) streams in behind the preceding cold front.
Scattered to isolated thunderstorms may develop and produce
isolated instances of excessive rainfall and flash flooding.

Upslope enhancement across the Sierra could produce heavier
rainfall totals than what are currently forecast. EAS probabilities
of 24 hour qpf exceeding 1 inch are over 40% in the Sierra and
between 15-40% in the Great Basin. Therefore, burn scars over
central and southern Idaho are at risk of flash flooding today.

...Eastern Florida...
Moist easterly flow into a surface front oriented north-south will
produce scattered convection across Florida today. The surface
boundary draped along the eastern coast will focus PWATs of around
2" in that area where MUCAPE between 500-1000 J/Kg will also likely
produce high rain rates. Neighborhood probabilities of exceeding
5" in 24 hours are between 40-90% from near Miami metro up through
Melbourne and Orlando.

Kebede


Day 2
Valid 12Z Fri Oct 03 2025 - 12Z Sat Oct 04 2025

...THERE'S A MARGINAL RISK FOR PORTIONS OF THE GREAT BASIN AND
EASTERN FLORIDA...

...Great Basin...
The upper trough propagates through the Great Basin and begins
lifting north on Friday. The excessive rainfall threat bleeds into
Friday from Thursday as thunderstorms weaken and spread from the
Great Basin into the Northern Rockies by Friday afternoon. Instability
and moisture will be relatively modest (100-200 J/Kg MUCAPE)
(0.5-0.9"). Ensemble exceedance probabilities of 1" are between
10-20% over northern Nevada with 2 day totals potentially eclipsing
2" in some places.

...Eastern Florida...
Moisture advection into Florida increases on Friday as a mid-level
circulation embedded within a broader upper ridge continues to
direct moisture and instability into the state's east coast.
Another inverted surface trough may develop along the state's east
coast and focus convection along the convergence zone. Ensemble
exceedance probabilities of 2" are between 5-15% along the
immediate coast, while first guess fields support the marginal with
5% flash flood probabilities.

Kebede


Day 3
Valid 12Z Sat Oct 04 2025 - 12Z Sun Oct 05 2025

...THERE'S A MARGINAL RISK FOR PORTIONS OF SOUTHEAST LOUISIANA AND
EASTERN FLORIDA INTO FAR SOUTHEASTERN GEORGIA...

...Central Gulf Coast...
Mid-level vorticity swirling over the Central Gulf Coast will
generate instability and pull an increasing amount of Gulf
moisture into the region on Saturday. Convection should fire along
a coastal convergence zone that develops and diurnal heating should
enhance afternoon/evening storms along that boundary. PWATs will
likely be over 2" with MUCAPE between 500-750 J/Kg. Ensemble exceedance probabilities of 2" are between 15-30% for much of southeast Louisiana.

...Eastern Florida/Southeastern Georgia...
Tropical moisture associated with Imelda will continue flowing into
Florida due to and upper ridge over the East Coast and embedded
troughing over Florida and the Gulf. A modest instability plume
should flow up the Florida Peninsula into far southeastern Georgia
where PWAT's of over 2" and an inverted surface trough could
combine to produce thunderstorms capable of generating 0.75-1"/hr
rain rates. Ensemble exceedance probabilities of 2" are between
5-15% along Florida's east coast into southeastern Georgia.


Kebede
$$
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FOUS30 KWBC 030743
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
343 AM EDT Fri Oct 3 2025

Day 1
Valid 12Z Fri Oct 03 2025 - 12Z Sat Oct 04 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
FLORIDA'S EAST COAST...

...Florida's East Coast...

A closed mid-level disturbance will drift westward across the
Florida Peninsula and into the Gulf of Mexico today. This system
will bring tropical moisture from Imelda and Humberto with it. An
inverted trough oriented along the Florida coast will interact with
the moisture advecting into the region and force scattered
thunderstorm activity throughout the day. Modest instability
between 500-1000 J/Kg MUCAPE could produce quarter to half inch
rates over the slight risk area. Parts of central and southern
Florida that have received between 2-4 (isolated 5) inches of rain
in the past 24 hours will be especially susceptible to runoff from
today's storms. Neighborhood exceedance probabilities of 5 inches
are between 20-40% across Florida's east coast today.

...Great Basin...

Additional rainfall is forecast to occur beneath the upper low,
which will continue propagating through the interior West today.
Recent heavy rainfall over portions of the Great Basin will likely
prime surfaces for runoff from additional precipitation. Burn
scars in central and southern Idaho continue to be of concern from
today's storms, the bulk of which should occur this morning into
afternoon before the upper low moves directly over the Great Basin
and instability weakens. HREF EAS exceedance probabilities of over
1 inch are between 15-35% over northern/central Nevada where PWATs
will be between 2-3 standard deviations above normal.

Kebede


Day 2
Valid 12Z Sat Oct 04 2025 - 12Z Sun Oct 05 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
FLORIDA'S EAST COAST...

...Florida's East Coast...

Thunderstorms are expected to continue to develop along the
inverted trough axis oriented north-south along Florida's east
coast on Saturday. Moisture will lift north along with the mid-
level disturbance. The inherited slight and marginal risk areas
were maintained due to a mostly consistent signal for excessive
rainfall over the east central coast. Ensemble exceedance
probabilities of 2 inches are between 5-10% across the marginal
risk area. 48 hour totals between 3-5 inches (local 6") will likely
make overcoming flash flood guidance a bit easier.

...Central Gulf Coast...

The same moisture regime impacting the Florida peninsula will focus
over the central Gulf Coast this weekend. Mid-level vorticity will
lift into the area on Saturday, providing forcing for convection
along the immediate Louisiana/Mississippi coast. Anywhere between
4-6 inches of rain may occur over far southeastern Louisiana
through Saturday night. Despite 2" ensemble exceedance
probabilities being relatively low (5-10%), the multi day nature
of the rainfall could still produce isolated instances of flash flooding.

Kebede


Day 3
Valid 12Z Sun Oct 05 2025 - 12Z Mon Oct 06 2025

...THERE'S A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE CENTRAL GULF COAST AND THE SOUTHEAST COAST...

...Central Gulf Coast...

The mid-level disturbance continues propagating westward toward the
positively tilted upper trough centered over the West on Sunday.
Thus, the heavy rainfall threat will likely bleed over from
Saturday evening into Sunday morning for portions of the Central
Gulf Coast, before dissipating beneath diminished support aloft.
PWATs of 2-2.5" and instability between 500-1000 J/Kg MUCAPE could
churn out rain rates between 1-1.5"/hr Saturday morning into
afternoon. Ensemble exceedance probabilities of 2 inches are
between 5-15% along the far southeastern Louisiana to Florida
panhandle corridor, which supports the marginal risk area in place.

...Southeast Coast...

Inverted troughing continues along the Florida/Southeast Coast
through the latter part of this weekend. Anomalous moisture (2-3
stndv) will continue interacting with the surface boundary to
generate scattered to isolated thunderstorms across the
Florida/Georgia coast. Rainfall totals of 1-3" are likely along
the Florida/Georgia/South Carolina coast on Saturday. The latest
guidance has trended away from tropical moisture making its way
inland, therefore a marginal risk was maintained for much of the
Southeast Coast.

Kebede
$$
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FOUS30 KWBC 040814
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
414 AM EDT Sat Oct 4 2025

Day 1 Valid 12Z Sat Oct 04 2025 - 12Z Sun Oct 05 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE EASTERN GREAT BASIN ALONG WITH THE CENTRAL GULF COAST AND
COASTAL GEORGIA DOWN THROUGH THE FLORIDA EAST COAST...

...Eastern Great Basin...

An amplifying upper-level trough advancing through the Great Basin
will be driving multiple waves of low pressure northeastward along
a frontal zone draped across the Intermountain Region. The latest
forecast guidance supports a strengthening mid to upper-level
closed low circulation pivoting across northern UT early this
morning before ejecting through western WY this afternoon. Strong
dynamics/DPVA will ride up across northern UT along with far
southeast ID and western WY which will be interacting with the
front and the pooling of modest instability (MLCAPE ~500 J/kg)
along it for an axis of locally heavy showers and thunderstorms.
Much of this threat will be this morning (notably in the 12Z to 18Z
time frame) as the height falls pivot across the region. The 00Z
HREF guidance suggests some organized convection that will be
capable of producing 1 to 2+ inches of rain which may include some
brief cell-training concerns for areas near and west of the
Wasatch front including around the Great Salt Lake. Can't rule out
there being at least some isolated runoff/flash flooding concerns
from these stronger clusters of convection that evolve this
morning. Therefore, a Marginal Risk of excessive rainfall has been
introduced, but this again is mainly for early in the period today.

...Central Gulf Coast...

A low to mid-level vort center/disturbance over the northern Gulf
of America is forecast to slowly advance westward today which will
help to bring stronger low-level southeast flow and moisture into
southeast LA and coastal MS. Sufficient low-level forcing associated
with the vort energy coupled with at least modest instability with
MLCAPE values of 1000 to 1500 J/kg will support there being at
least scattered bands of convection that will develop and advance
inland across the central Gulf Coast. Some of the 00Z HREF guidance
and recent RRFS solutions suggest some linearly oriented convective
bands potentially setting up that would support some locally
enhanced rainfall totals. Given the improving PW environment with
values of 1.75 to 2+ inches, and a convergent southeast low-level
jet of 30+ kts, some of the rainfall rates may reach or exceed 2
inches/hour. The potential banded nature of the activity may
support some localized rainfall totals going into early Sunday
morning of 2 to 4+ inches. These rains will pose at least an
isolated threat for flash flooding, and especially if any of these
heavier rains were to make into the New Orleans metropolitan area.
As such, a Marginal Risk of excessive rainfall has been introduced
for this period for the central Gulf Coast.

...Coastal Georgia and the Florida East Coast...

Low-level easterly flow will persist today and tonight across the
FL East Coast given the placement of a well-established area of
surface high pressure farther north over the Mid-Atlantic states.
However, the surface ridging is forecast by the models to shift
offshore by later today which will allow for some veering and
strengthening of the Atlantic fetch a bit farther north up into
coastal areas of eastern GA. The latest hires model guidance
suggests a stronger axis of low-level moisture convergence along
with pooling of instability into coastal areas of eastern GA and
near the SC border. Some locally focused bands of relatively shallow/warm-topped convection may attempt impact the coastal
areas here, with some guidance suggesting locally a couple inches
of rain being possible. Farther south, the FL East Coast should
continue to see scattered to broken areas of showers and
potentially a few thunderstorms. However, the activity should
remain disorganized given a lack of deeper layer forcing and only
modest low-level convergence along the coast. The Slight Risk area
that was inherited for the FL Space Coast vicinity has been removed
in favor of a Marginal Risk which will include the north/south
length of the FL East Coast, but extending northward now to the
SC/GA border. Any runoff concerns from heavy rainfall will tend to
be highly isolated and primarily focused over the more urbanized areas.

Orrison


Day 2 Valid 12Z Sun Oct 05 2025 - 12Z Mon Oct 06 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE CENTRAL GULF COAST, THE SOUTHEAST COAST, AND THE CENTRAL PLAINS...

...Central Gulf Coast...

A weak disturbance in the western Gulf will likely continue to focus
enhanced convergence and convection along portions of the central
Gulf Coast into Sunday. Heaviest rainfall totals may tend to stay
just offshore where the better instability will reside...although
coastal convergence and instability into the immediate coastline
should allow for some heavier cells to make it onshore. Even our
deterministic QPF, which is a multi model blend, brings two day
rainfall totals as high as 3-5" over far southeast LA and right
around 3" along coastal MS and AL. Given the convective nature of
rainfall and PWs over 2" would expect totals to locally exceed these
amounts, and isolated instances of flash flooding are possible. The
00z REFS probabilities of 8" is over 90% across coastal MS/AL. This
is seemingly an under dispersed ensemble in this case, but
interesting nonetheless, and possibly indicative of a lower
probability worst case scenario. Either way, will need to continue
to monitor trends, as can not rule out the need for a Slight risk
along portions of the immediate coast.

...Southeast Coast...

The model QPF signal continues to trend down across the Southeast
coast, although onshore easterly flow, coastal convergence and PWs
around 2" will support localized instances of heavy rainfall.
Overall the flash flood risk appears pretty low, but an isolated
threat can not be ruled out.

...Central Plains...

Convection will likely expand in coverage Sunday evening across
portions of northeast KS, southeast NE and southwest IA. A stalling
frontal boundary will allow for persistent moisture convergence in
the lower levels coupled with a divergence signature aloft. Thus it
seems probable that rainfall will persist through much of the night,
not moving all that much over that time. Whether we see any flash
flood risk evolve will likely come down to the degree of instability
present. It seems likely that we will initially have enough
instability for deeper convection and 1"+ an hour rainfall. However
most indications are that this instability axis will be rather
narrow and under 1000 j/kg. Thus would expect that instability to
get eroded fairly quickly, resulting in decreasing rainfall rates
overnight. Nonetheless, our latest deterministic QPF has 1-2" of
rain, with 2-3" if you include the rain that continues into Monday.
When accounting for convection resulting in locally heavier amounts,
and the possibility that instability ends up greater than forecast
(which a couple models show) then a low end flash flood risk can not
be ruled out.

Chenard


Day 3 Valid 12Z Mon Oct 06 2025 - 12Z Tue Oct 07 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS EASTERN
FLORIDA AND THE CENTRAL PLAINS...

...Eastern FL...

The 00z ECMWF, AIFS and GEFS mean all suggest an increase in
convective coverage over eastern FL on Monday compared to Sunday.
The approach of a subtle mid level wave may help increase low level
easterly moisture transport while also providing a bit more in the
way of upper divergence. Isolated urban flash flooding should thus
remain a threat into Monday, although would anticipate the risk to
stay quite localized. There has been a clear model trend away from
bringing heavier rainfall into SC/GA and thus the northern extent of
the Marginal risk was cut back.

...Central Plains...

Some convection will likely be ongoing Monday morning across
portions of northeast KS, southeast NE, southwest IA and northwest
MO. The stalled front will remain in the area through the day likely
helping focus additional convection that should only slowly drift
southward. Instability should increase Monday along this front,
however this will coincide with a decrease in moisture transport and convergence along the front. Thus not really anticipating anything
more than a very localized flash flood risk. The threat is likely a
lower end Marginal risk, but given the slow front and two day
rainfall totals of 2", to perhaps as high as 3-4", across this
corridor, localized flooding can not be ruled out. We will maintain
the inherited Marginal risk, but shrink to to better coincide with
the axis of highest two day rainfall totals.

Chenard
$$
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FOUS30 KWBC 050819
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
419 AM EDT Sun Oct 5 2025

Day 1 Valid 12Z Sun Oct 05 2025 - 12Z Mon Oct 06 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE CENTRAL PLAINS AND MIDWEST ALONG WITH THE CENTRAL GULF COAST
AND EASTERN FLORIDA...

...Central Plains/Midwest...

In the wake of an upper-level trough and surface low transiting
portions of the northern Plains, a cold front will be gradually
settling southeastward today and tonight across the central Plains
and Midwest. Showers and thunderstorms are expected to develop
along the front by this evening across areas of central and
northern KS up through southeast NE and through central IA. MLCAPE
values as high as 1000 to 1500 J/kg are forecast to pool along the
boundary along with a seasonably moist airmass characterized by PWs
of 1.25 to 1.5+ inches. Moisture transport along the front will be
aided by a southwest low-level jet of 30 to 40+ kts going through
00Z this evening which coupled with the instability should help
drive some heavier rainfall rates capable of reaching 1 to 1.5
inches/hour. Going through Sunday night, the convection is expected
to linger as at least modest right-entrance region upper jet
dynamics overhead continue to interact with the front. Some post-
frontal shower and thunderstorm activity is expected as a pool of
elevated instability and frontogenesis lingers over the region. A
consensus of the 00Z HREF guidance supports some spotty 2 to 3+
inch rainfall totals in a narrow axis along the front. Antecedent
conditions are quite dry, but with some localized cell-training
concerns and heavier rainfall totals, there may be some isolated
and mainly urbanized runoff concerns. A Marginal Risk of excessive
rainfall will be maintained across the region.

...Central Gulf Coast...

An elongated low to mid-level low center/trough over the northwest
Gulf of America is expected to focus a corridor of stronger
convergence and moisture transport across the central Gulf Coast
region, with potential for multiple bands of very heavy showers and thunderstorms to evolve. The convection will be embedded within a
deep tropical environment characterized by PWs of 2 to 2.25
inches. This coupled with MLCAPE values of locally near 1500 J/kg
will help favor high rainfall rates that may easily reach 2 to 3
inches/hour with the stronger and more organized convective bands.
The 00Z HREF guidance generally supports the heaviest rainfall
totals remaining confined to the immediate Gulf Coast, however some
localized bands of convection that will be capable of cell-
training may be able to spread a bit farther inland including areas
of south-central to southeast LA through far southern MS and far
southern AL. Some urbanized Gulf Coast locations including New
Orleans and Mobile may be impacted going through Sunday night by
bands of heavy showers and thunderstorms. The latest REFS/RRFS
guidance is more aggressive with the rainfall potential, but a
HREF-led consensus of guidance would suggest some 2 to 4 inch
rainfall totals with spotty 5+ inch amounts not out of the question
where any cell-training occurs. The Marginal Risk area will be
maintained for the time being, with isolated areas of flash
flooding possible, and especially for the aforementioned urban
corridors. However, should the guidance trend any wetter, a Slight
Risk upgrade may be warranted for portions of the central Gulf Coast.

...Eastern FL...

Moist and locally convergent low-level easterly Atlantic flow will
continue along the FL East Coast today. There are some locally
heavier rainfall signals showing up along the Space and Treasure
Coasts and stretching inland somewhat as the potential once again
for some broken bands of locally heavy showers and thunderstorms
sets up. Where any cell-training occurs within these bands, some
spotty rainfall totals of 2 to 4+ inches will be possible. This
may result in there being a highly localized concern for some
runoff problems. A Marginal Risk of excessive rainfall will be
maintained at this time.

Orrison


Day 2 Valid 12Z Mon Oct 06 2025 - 12Z Tue Oct 07 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
EASTERN ARKANSAS INTO THE OHIO VALLEY AND OVER EASTERN FLORIDA...

...TN and OH Valley...

A Marginal risk was maintained from portions of eastern AR
northeastward into southern IN. 850mb vorticity fields indicate the
tropical disturbance in the Gulf is likely to lift northward on
Monday brining increased PWs and the potential for areas of slow
moving convection. Scattered convection is expected during the day,
although the better focus for high rainfall amounts should come
Monday night as the approaching cold front from the west helps
increase convergence. The environment appears to favor efficient
warm rain processes...with the presence of the low level vorticity
from the Gulf and PWs around or above 2" (over the climatological
90th percentile). Only weak instability is forecast, which could end
up being a limiting factor for flash flooding. However, given the
expected efficient warm rain, there should still be enough
instability to get hourly rainfall rates into the 1-2" range in
spots. The latest WPC deterministic QPF is 1-2" across the area,
although several models indicate locally higher amounts. Given the
environment in place amounts locally getting into the 2-4" range
seems reasonable within the Marginal risk area.

Expect at least localized instances of flash flooding to be
possible, especially by Monday night. There is a bit of uncertainty
regarding the exact rainfall axis, with the new 00z ECMWF shifting
farther east into more of TN and KY. The eastern extent of the
Marginal risk was extended in this direction to account for this potential...although the broader model consensus still favors a
slightly farther west axis, in line with the WPC QPF.

...Eastern FL...

Easterly low level flow will continue to support scattered
convection over eastern FL Monday into Monday night. Model guidance
continues to depict a modest uptick in rainfall coverage and
magnitudes on Monday compared to Sunday. Localized urban flash flood
impacts will remain possible.

...Central Plains...

We opted to remove the Marginal risk that stretched from northeast
KS into southern IA with this update. A localized flash flood risk
still exists on day 1, but by Monday the areas hit hardest on day 1
will be well north of the surface front. Thus most of the
instability will be gone, and rainfall rates should be much lower.
Thus the additional rainfall is not expected to be enough to result
in flash flooding. A bit more instability may reside over MO, but
this is south of the forecast rainfall axis on Sunday, and thus the
rainfall Monday is not expected to be enough to overcome the drier
antecedent conditions here.

Chenard


Day 3 Valid 12Z Tue Oct 07 2025 - 12Z Wed Oct 08 2025

...THERE IS MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE TENNESSEE AND OHIO VALLEY, OVER SOUTHEAST FLORIDA, AND PORTIONS
OF NEW MEXICO...

...TN and OH Valley...

A Marginal risk was maintained from TN northward into portions of OH
and southwest PA. Increasing moisture ahead of an approaching cold
front will likely lead to greater convective coverage and areas of
heavy rainfall. The forcing and moisture will be enhanced by the
same low level vorticity feature that was upstream on Monday and
over the Gulf on Sunday. With PWs forecast over the climatological
90th percentile do expect some warm rain processes, which should
help overcome marginal instability and help produce heavy rainfall
rates. Also note a well defined upper divergence signature centered
over this region within the right entrance region of an upper jet.
Thus the ingredients are there for widespread rainfall and at least
some pockets of heavy rates.

The main question for flash flood potential will be the duration of
these higher rates. Overall the front looks pretty progressive,
which should limit this duration. However, guidance does indicate
that some training could occur for a period Tuesday before the front
clears through, with the favored axis somewhere in the vicinity of
central to eastern KY. While differing on location, most 00z
deterministic models indicates a swath of 2-3" of rainfall, which
seems reasonable given the environment in place. In fact would not
be surprised if totals locally exceed 3". Overall this seems like a
solid Marginal risk with localized areas of flash flooding probable.
Can not rule out an embedded Slight risk upgrade on future updates
pending model trends.

The northern extent of the Marginal risk was cut out of the
Northeast with this update. Instability really drops off with
northern extent which will impact rainfall rate potential. These
lower rates combined with the drought conditions suggest flash
flooding is unlikely. We would probably need higher rates to overcome
the dry soil conditions, and this seems unlikely given the currently
forecast instability. So it is looking more like a beneficial
rainfall, with most areas around 0.75" but locally as high as 1.25" or so.

...Southeast FL...

Expecting another day of scattered convection within the easterly low
level flow Tuesday. Compared to previous days the threat should
mostly be focused over southeast FL by this time, and a localized
urban flash flood risk is possible.

...NM...

A Marginal risk was maintained for portions of central and eastern
NM on Tuesday. Easterly low level post frontal flow will help
locally enhance convergence and upslope and scattered convection is
likely to develop. With PWs around 1" and CAPE only forecast between
500-1000 j/kg this is likely a lower end threat. Nonetheless,
locally heavier convection with high rates could result in isolated
flash flooding, particularly over any more sensitive burn scars or
basins.

Chenard
$$
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FOUS30 KWBC 060819
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
419 AM EDT Mon Oct 6 2025

Day 1
Valid 12Z Mon Oct 06 2025 - 12Z Tue Oct 07 2025

...THERE IS SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE MID-SOUTH AND LOWER OHIO VALLEY...

...Mid-South/Lower Ohio Valley and the Central Gulf Coast...

An elongated low to mid-level vort center near the central Gulf
Coast will lift northward into the Mid-South today and gradually
stretch northeastward into portions of the Lower OH Valley by later tonight through early Tuesday morning. Increasingly convergent flow around
the eastern flank of the vort energy and an associated weak surface
low/trough axis coupled with enhancing moisture transport aided by
a 30 to 40 kt low-level jet will support broken bands of heavy
showers and thunderstorms. Modest instability with MLCAPE values of
500 to 1000 J/kg will be in place with the aid of diurnal heating,
but the vertical column will be quite moist with CIRA-ALPW data
showing the aforementioned vort energy embedded within a rather
deep tropical environment characterized by PWs of 2 to 2.25 inches.

Relatively warm-topped convection with high WBZ levels will support
very efficient rainfall processes for high rainfall rates as this
energy lifts north over the next 12 to 24 hours. The latest 00Z
HREF guidance supports broken convection with rainfall rates as
high as 1.5 to 2.5 inches/hour, and some concerns for some cell-
training that may foster some localized totals of 3 to 5 inches.
The more concentrated areas of convection are most likely to focus
across areas of eastern AR/western TN northeastward up into western
KY and southern IN going through Monday night and Tuesday morning
where the axis of stronger low-level convergence in conjunction
with some modest upper-level jet forcing/divergence is forecast to
become aligned. A Slight Risk of excessive rainfall will be
maintained for this period, with some southward expansion of it
depicted down across eastern AR compared to continuity given the
latest multi-model hires consensus. The setup will be conducive
for there being isolated to scattered areas of flash flooding which
will include urbanized flooding concerns.

Meanwhile, very moist and convergent low-level southerly flow off
the Gulf coupled with a moderately unstable boundary layer will
favor a threat for additional small-scale bands of convection to
impact parts of eastern LA along with coastal areas of southern
MS, southwest AL and into the western FL Panhandle. PWs running
close to or above 2 inches coupled with the instability will yield
high rainfall rates, with some localized additional rainfall totals
for this period of 2 to 4+ inches possible. This is supported by
the 00Z HREF guidance, and the setup will support isolated concerns
for runoff problems/flash flooding. As a result, a Marginal Risk
of excessive rainfall has been expanding to encompass these areas.

...Eastern FL...

Moist easterly low-level flow will continue to support scattered
areas of convection over eastern FL today through tonight. The
activity again should tend to be rather disorganized, but there
will be some potential for small-scale east/west oriented bands to
set up that may result in some isolated 2 to 4+ inch rainfall
totals. This may drive at least some isolated runoff concerns. As a
result, the Marginal Risk of excessive rainfall is maintained for
this period.

Orrison


Day 2
Valid 12Z Tue Oct 07 2025 - 12Z Wed Oct 08 2025

...THERE IS SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE OHIO VALLEY...

...Ohio Valley into the Central Appalachians...

A Slight risk was maintained from portions of northern TN into much
of KY, southern IN and OH, and western WV where isolated to
scattered flash flooding is likely. Increasing southerly flow ahead
of an approaching cold front will advect moisture northward while
also enhancing lower level convergence. Also of note is a sfc-850mb
low that is over AR today and was over the northern Gulf on Sunday.
This feature will get more elongated in nature by Tuesday, but
should still act to locally increase moisture transport and
convergence over KY and surrounding areas. PWs are forecast around
2", which is well over the 90th percentile for this time of year.
Instability is expected to only be modest, generally in the 500-1000
j/kg range, however the strong synoptic forcing provided by the
approaching front and good upper level divergence should compensate
for this and still allow for organized convection.

Both the 00z HREF and REFS show moderate to high probabilities of
hourly rainfall exceeding 1", but only low probabilities of
exceeding 2". The limited instability is likely responsible for
the lack of 2"+ per hour rainfall rates. However the deep saturated
layer and low topped convection supports highly efficient warm rain collision-coalascence processes, leading to the likelihood of at
least 1" per hour rainfall.

The main question for flash flood potential will be the duration of
these higher rates, as it seems unlikely that 1hr FFG will be
exceeded. While the front will be progressive, it does look like we
will have enough convective coverage to support some training, and
at least a few hours of heavy rainfall rates. Thus while 1hr FFG may
be difficult to overcome, it does look like there will be an
opportunity for some exceedance of the 3hr FFG...with both the 00z
HREF and REFS showing exceedance probabilities upwards of 25-50%.
The latest WPC QPF indicates event total rainfall of 2-4" over most
of the Slight risk area, which is supported by high HREF and REFS
neighborhood probabilities of exceeding 3". Also will note that
there are even moderate probabilities of locally exceeding 5" with
this event.

There is a bit of model spread on the most favored axis for heaviest
rainfall and flash flooding. Both the HREF and REFS supports a
slightly farther southwest axis across KY and northern TN, with the
global guidance generally more over eastern KY into WV. The Slight
risk was made big enough to support a compromise of these two camps,
and will need to continue to monitor trends going forward. Generally
think the highest risk is over KY, but can no rule out that shifting
into northern TN or portions of WV.

While the rainfall does look a bit more convective now over the
Northeast, 1" per hour probabilities are still low...with most
guidance peaking rainfall rates in the 0.5"-0.75" range. Given the
ongoing drought conditions it still seems unlikely that these rates
will be high enough to overcome the dry soil conditions. Thus even
with rainfall totals approaching 1.5" we will continue with no risk
area depicted.

...Southeast FL...

Expecting another day of scattered convection within the easterly low
level flow Tuesday. Compared to previous days the threat should
mostly be focused over southeast FL by this time, and a localized
urban flash flood risk is possible.

...NM...

The convective threat looks a bit better than it did this time last
night with models trending a bit more robust with development.
Easterly low level post frontal flow will help locally enhance
convergence and upslope and scattered convection is likely to
develop. Instability is forecast to be modest, but may get towards
1000 j/kg, which would be enough for heavy rainfall rates given the
anomalous PWs in place. The high res guidance is starting to show a
threat of 1"+ per hour rainfall, which would be enough for isolated
flash flooding.

Chenard


Day 3
Valid 12Z Wed Oct 08 2025 - 12Z Thu Oct 09 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
NEW MEXICO...

Looking at a continuation of the localized heavy rainfall threat over
NM into Wednesday. The moisture plume and instability axis will
expand westward which should expand the isolated flash flood risk in
that direction as well. The environmental ingredients look pretty
similar to Tuesday, as do model QPF forecasts. So would generally
expect similar convective coverage and intensity with isolated flash
flooding again a concern.

Chenard
$$
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FOUS30 KWBC 070829
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
429 AM EDT Tue Oct 7 2025

Day 1
Valid 12Z Tue Oct 07 2025 - 12Z Wed Oct 08 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
KENTUCKY, MIDDLE TENNESSEE, THE UPPER OHIO VALLEY, AND NEW MEXICO...

...Mid-South through the Upper Ohio Valley and Central Appalachians...

A weak mid-level vorticity maxima (currently over far northeastern
Arkansas) will trek east-northeastward across Kentucky through
most of the day. This feature will likely maintain at least some of
its organization given persistent convection near and east of its
center and sufficient downstream instability. Areas of 1-3 inch
rainfall totals are expected with this feature, and an uptick in
convective coverage should occur later today as surface heating
promotes destabilization within a moist airmass downstream of the
feature. Slow cell movement and localized training/backbuilding are
both expected to prompt areas of excessive runoff through the
forecast period especially within the Slight Risk area.

Later today, height falls from a larger scale trough centered over
Hudson Bay will aid in additional convection along a front that
will sweep through the region. Storms may redevelop across Kentucky
and Tennessee, although the degree of coverage will be heavily
modulated by the degree of lingering instability behind the initial
wave of daytime convection expected across those areas. A pool of
at least 1.5 inch PW values should remain - supporting heavy
rainfall with any lingering convection through the evening hours.

Additional convection is expected along the aforementioned cold
front across New York State and western New England. Storm motions
should be relatively fast (30+ knots), limiting any heavy rainfall
to any localized areas of training that can materialize.
Additionally, antecedent dryness/drought should limit excessive
runoff potential. A Marginal risk extends to western Pennsylvania
and vicinity - although this risk seems a bit too isolated farther
northward to include or expand in any probabilities at this time.

...New Mexico...

A southwestward moving cold front will stall close to the higher
terrain across central New Mexico today through tonight. Upslope
flow behind this front and weak mid/upper waves traversing the
state will both initiate deep convection within a sufficiently
moist airmass (0.7-1.25 inch PW) for heavy rainfall. Storm motions
across northern portions of the state may be quick enough to limit
rainfall, yielding a mostly isolated flash flood threat in areas
that are sensitive (i.e., burn scars, low-lying areas). Central and
southern portions of the state should experience slower storm
motions and perhaps multiple rounds of convection from afternoon
through the overnight hours. Given increase in convective coverage
and potential for local 3+ inch rainfall totals occurring
perilously close to sensitive areas/burn scars, a Slight Risk was
introduced with the expectation of at least a few instances of
excessive runoff given the scenario.

...Southeastern Florida...

Local 1-2 inch rainfall totals are expected across urban areas of
Southeastern Florida from Miami northward through West Palm Beach
and Port Saint Lucie. The greatest risk of these downpours
materializing will occur from midday onward due to peak heating/destabilization. Additionally, onshore flow/coastal
flooding may hinder runoff processes beneath any heavier downpours,
locally enhancing flash flood risk. One or two instances of flash
flooding cannot be ruled out, and a Marginal Risk is in place to
address the threat.

Cook


Day 2
Valid 12Z Wed Oct 08 2025 - 12Z Thu Oct 09 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF NEW MEXICO AND EASTERN ARIZONA...

Some continuation of heavy rainfall potential will exist across New
Mexico during the early morning hours of the D2/Wed forecast
period. During the day, an increase in insolation/destabiliztaion
should promote development of isolated to scattered thunderstorms
initially along terrain/ridgelines near the Arizona/New Mexico
border and across the southern Rockies. Storms will drift
slowly/erratically while producing brief heavy rainfall. Typical
low spots/sensitive areas will experience a flash flood threat with
this activity. Coverage of flash flood potential should be sparse
enough to warrant continuation of a Marginal Risk and associated
probabilities.

Cook


Day 3
Valid 12Z Thu Oct 09 2025 - 12Z Fri Oct 10 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS A LARGE
PART OF THE SOUTHWEST AND SOUTHEASTERN FLORIDA...

...Southwest...

Models are consistent in depicting a dramatic increas in
atmospheric moisture content across the Colorado River Valley from
both Hurricane Priscilla and the Gulf of California. Widespread
1-1.75 inch PW values are expected by midday Thursday. This
moisture will combine with deep southwesterly steering flow and
weak mid-level waves aloft to produce several areas of
precipitation throughout the forecast period (including the
overnight and early morning hours). A close inspection of point
forecast soundings from model data casts some doubt on the extent
of instability developing within the moist axis due to widespread
cloud cover. Any daytime destabilization within the region will
likely lead to stronger convection and an increased risk of flash
flooding. Trends in instability will be monitored for possible
upgrades in parts of the Marginal Risk area in later outlooks.

...Southeastern Florida...

Models depict a few areas of convection developing very close to
urbanized areas of southeastern Florida during peak heating hours.
Point forecast soundings across the area depict typically
moist/unstable profiles (2+ inch PW values), though wind fields are
very weak, suggesting slow/erratic cell movement and mergers. Spots
of 1-3 inch/hr rain rates could materialize, supporting an urban
flash flood risk across the area.

Cook
$$
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FOUS30 KWBC 080809
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
409 AM EDT Wed Oct 8 2025

Day 1
Valid 12Z Wed Oct 08 2025 - 12Z Thu Oct 09 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF NEW MEXICO AND EASTERN ARIZONA...

Ongoing shower and thunderstorm activity will exist on an isolated
basis across central and south-central New Mexico near higher
terrain. Slow movement, localized backbuilding, and proximity to
burn scars will be the likely modulators of flash flood potential
through the early morning hours.

Later in the afternoon, thunderstorm activity is expected to
develop across western New Mexico and eastern Arizona in an
environment characterized by 0.7-1.0 inch PW values, mid-level
instability, and weak wind fields beneath 500mb. Slow moving cells
with brief heavy rainfall are likely, though coverage should remain
isolated. The greatest flash flood threat should exist where
heavier rain can materialize in/near typical low spots/burn scars.
Most of this activity should be diurnally driven, with weakening
expected in tandem with low-level stabilization after the 03-06Z timeframe.

Cook


Day 2
Valid 12Z Thu Oct 09 2025 - 12Z Fri Oct 10 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHWEST AND EASTERN FLORIDA...

...Southwest...
Moisture content across much of the Southwestern U.S. will increase dramatically in tandem with strengthening southerly mid-level flow
downstream of a mid-level trough along the California coast and
trajectories emanating from Hurricane Priscilla. Modest surface
heating will allow for areas of convection to drift northeastward
across the Marginal Risk area throughout the day - perhaps
beginning as early as 12Z Thursday. Models depict the greatest risk
of deeper convection occurring from northwestern Arizona into
southwestern Utah during the afternoon/evening, and some of this
development could extend into southern Nevada as well. Additional
thunderstorm activity may occur across the eastern Transverse and
Peninsular Ranges in southern California on an isolated basis. The
primary mitigating factor for a more widespread flash flood risk
is limited insolation/surface warming due to cloud cover. One or
two focused corridors for heavier precipitation may develop within
the broader Marginal contingent on stronger destabilization due to
afternoon sunshine. Should this scenario materialize, a small area
of higher probabilities/ and categorical Slight Risk may be needed.

...Florida...
Models (particularly CAMs) depict deep moist convection across the
east coast of Florida during the afternoon and evening hours. As
typical for the region, abundantly moist thermodynamic profiles
will combine with weak kinematics for slow-moving cells with local
2-3 inch/hr rates at times on an isolated basis. These cells will
pose an urban flash flood threat from Daytona Beach southward to
Miami/Dade metro. Weak onshore flow has also contributed to a
coastal flood risk that might hinder runoff potential and
exacerbate flood concerns on a localized basis.

Cook


Day 3
Valid 12Z Fri Oct 10 2025 - 12Z Sat Oct 11 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS NORTHERN
ARIZONA, SOUTHERN UTAH, AND SOUTHWESTERN COLORADO...

...Southwest...
A second consecutive day of abundant moist advection will be
underway during the D3 forecast period as Priscilla drifts
northward and a slow-moving mid-level trough persists along the
California coastline. Models are generally higher with instability
parameters (500-1000 J/kg MUCAPE) compared to prior days across
the Marginal and Slight Risk areas while maintaining abundantly
moist profiles (PW values ranging from 1-2 inches). Areas of
heavier rain are expected, with deeper convection possible in the
Slight Risk area from northern Arizona into southwestern Colorado.
Some of these heavier downpours will occur atop sensitive
terrain/slot canyons and burn scars - posing a locally significant
flash flood risk. While specific timing of convection remains a
challenge at this timeframe, it is possible that multiple rounds of
convection develop and migrate northeastward across the region
throughout the forecast period. Widespread 1 inch rainfall totals
are expected, with local amounts potentially exceeding 3 inches in
a few spots.

...Southeastern U.S. Coastline...
Models are in agreement that a low pressure will develop and
strengthen substantially over the Gulf Stream just east of Florida
during the forecast period. Low-level easterlies will strengthen
dramatically and eventually become northeasterly during the
forecast period. These low-level wind fields will contribute to a
coastal flood risk while also hindering runoff processes near areas
that experience heavy rainfall. The heavy rainfall threat is a bit
conditional especially with northward extent across the Carolinas
coastlines. Nevertheless, model guidance generally depicts a few
areas of heavy rainfall especially across eastern Florida during
the first half of the Day 3 forecast period (Friday morning).
Trends will need to be monitored for any westward trend in
development of this low closer to land areas, which may increase
the heavy rainfall threat substantially. At this time, isolated
flash flood/runoff issues are expected, warranting continuation of
a Marginal Risk along coastal areas.

Cook
$$
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FOUS30 KWBC 090745
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
345 AM EDT Thu Oct 9 2025

Day 1 Valid 12Z Thu Oct 09 2025 - 12Z Fri Oct 10 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEASTERN
CALIFORNIA, SOUTHERN NEVADA, SOUTHWESTERN UTAH, AND WESTERN ARIZONA...

...Southwest...

Models/observations all continue to suggest that a dramatic
increase in low- and mid-level moisture content should occur across
the Southwestern U.S. in tandem with eastward movement of a broad
mid-level trough just west of California and moist mid-level
trajectories emanating from Priscilla. At least a few pockets of
surface heating should occur beneath the moisture plume, resulting
in sufficient surface-based instability for deeper convection
during the afternoon and evening. Efficient rainfall processes
should occur with any storms that form due to the aforementioned
moisture content (with PW values reaching nearly 2 inches across
southwestern Arizona/far southeastern California). Mid-level wind
fields suggest potential for appreciable (20-30 knot) storm
motions, although the tendency for convection to train and occur
on/near sensitive ground conditions (i.e., burn scars, slot
canyons) are all suggestive that at least a few instances of flash
flooding can be expected during the forecast period. Models are
also suggestive of continued precipitation potential overnight
despite a loss of surface heating - likely due to ascent from both
Priscilla and the mid-level trough off the West Coast. Several
areas of 1 inch rainfall totals are possible, and isolated 2-2.5
inch totals could also occur.

...Florida...

Models continue to produce deep moist convection across the east
coast of Florida during the afternoon and evening hours. Widespread
1-3 inch rainfall amounts are expected. As typical for the region,
abundantly moist thermodynamic profiles will combine with weak
kinematics for slow-moving cells with very high rainfall rates
(exceeding 2 inches/hr at times). These cells will pose an
urbanized flash flood threat from Jacksonville metro southward
through Miami/Dade. Weak onshore flow has also contributed to a
coastal flood risk while hindering runoff processes in a few
locales. This could exacerbate flood/flash flood concerns on a
localized basis.

Cook


Day 2 Valid 12Z Fri Oct 10 2025 - 12Z Sat Oct 11 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF ARIZONA...

...Southwest...

A synoptically evident heavy rain threat is expected to unfold
across the region Friday into early Saturday. Models continue to
depict a large-scale trough just west of the California coastline
that should slowly move eastward and spread geopotential height
falls across much of the Southwest and Great Basin. 00Z models have
sped up the timing of the absorption of Priscilla (perhaps
remnants of Priscilla by this forecast timeframe) within the
broader-scale trough and now depict them directly impacting
portions of Arizona by as early as 18Z Friday. Ascent from
Priscilla, ascent from the larger-scale trough, and abundant
moisture streaming into much of the Great Basin (with attendant
terrain influences) all point to potentially widespread flash
flooding during the forecast period. Of note - the overall synoptic
pattern has notable parallels to early October 2018, when remnants
of Hurricane Rosa moved into the Great Basin and prompted
extensive flash flood impacts across central Arizona.

The Moderate Risk has been introduced across portions of central
into northeastern Arizona where models (particularly the GFS and
ECMWF) depict multiple hours of repeating thunderstorm potential
especially focused near terrain-favored areas of the Mogollon Rim.
Widespread 1-2 inch rainfall amounts (and locally higher totals)
can be expected. Significant impacts are possible given the
prolonged heavy rainfall potential. While specific timing of
convective axes are still unclear at this timeframe, some eastward
progression of the heaviest rainfall is generally depicted by most
model guidance, with precipitation areas potentially reaching the
AZ/NM border region through 12Z Saturday.

Outside of the Moderate Risk area, models depict potential for
scattered thunderstorms to occur throughout the forecast period
from southeastern California northeastward through eastern Utah and southwestern Colorado. A few instances of flash flooding will
remain possible especially near urban areas, burn scars, and slot canyons.

...Southeastern U.S. Coastal Areas...

Models continue in agreement that an organizing area of low
pressure will strengthen over the southern Gulf Stream (east of
Florida) during the forecast period. Models are also in agreement
that at least a few spots along the coast will experience heavy
rainfall at times through 12Z Saturday - especially in eastern
Florida. This heavy rainfall potential will occur in conjunction
with dramatically strengthening onshore flow across coastal areas
that should promote flooding while hindering runoff. This "combo-
flood threat" (both freshwater and saltwater flooding) will exist
across coastal areas throughout the forecast period while peaking
fairly early across the east coast of Florida (between 12Z Friday
and 00Z Saturday) and peaking across coastal Carolinas areas from
00Z Saturday through the end of the forecast period (12Z Saturday).

Cook


Day 3 Valid 12Z Sat Oct 11 2025 - 12Z Sun Oct 12 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
FOUR CORNERS STATES AS WELL AS FOR PORTIONS OF COASTAL NORTH
CAROLINA AND VIRGINIA...

...Southwest...

Predominant southwesterly flow ahead of a deep longwave trough
progressing east from the West Coast to over the Intermountain West
will draw plentiful tropical moisture from the remnants of Priscilla
into the Four Corners Region. This will spike atmospheric moisture
levels over portions of Arizona to as high as 5 sigma above normal.
Thus, moisture availability for rainfall will not be a limiting
factor in the slightest (pun intended). However, what will limit the
potential for more significant flooding will be a lack of
instability. While the remnants of Priscilla will bring some
instability northward, for most areas MUCAPE values are expected to
remain under 1,000 J/kg. Thus, the areas of heaviest rainfall will
be focused on south and west facing slopes, as upslope becomes a
primary localized forcing mechanism. With a Moderate Risk upgrade on
Day 2, a higher end Slight is in effect for the portions of the
Mogollon Rim expected to be hardest hit from the aforementioned
upslope continuing into Day 3.

The Slight up to the 4 Corners/southwest Colorado remains unchanged
with this update. Similar to further south and west, upslope will be
a primary forcing mechanism, in addition to the upper divergence
ahead of a strong shortwave which will push east from California to
over Utah by Sunday morning. This too will locally increase the
forcing needed to squeeze out additional rainfall into the San Juans
throughout the period.

Finally, the inherited Marginal Risk was expanded north to cover
much of central Montana with this update. Additional shortwave
energy, perhaps moving even faster than the energy further south,
will allow for a localized negative tilt to the shortwave, which
should greatly increase the forcing needed for widespread light to
moderate rainfall into central Montana. A potent cold front
associated with the approach of the upper level trough will also
locally increase rainfall rates ahead of the front. See the Heavy
Snow Discussion (HSD) for additional details on the snowfall
potential in the higher elevations of western Montana with this same disturbance.

...Mid-Atlantic Coast...

The center of a large and slow-moving Nor'easter will make its way
up the coast from off Jacksonville, FL Saturday morning to near
Wilmington, NC by Sunday morning. The expansive precipitation shield
associated with this large low will be impacting the coast of the
Carolinas already at the start of the period, with its northernmost
extent moving into southern New England by the end of the period
Sunday morning. The biggest rainfall threat with this storm will be
across coastal North Carolina and Virginia. The guidance is in
reasonable agreement that once the center reaches near the border of
the Carolinas, it's forward speed will slow to a crawl through
Saturday night. This will allow the comma-head region of the storm
to sit in place across coastal North Carolina and Virginia for a
long-duration, likely lasting into the D4/Sunday period. Meanwhile
strong and gusty northeast winds will pile up tidal/ocean water at
the coast. While coastal flooding concerns are likely to be a much
more significant concern as far as magnitude of impacts, ocean water
backing up the mouths of bays, rivers, and inlets is likely to
significantly impede draining the fresh water that falls from
rainfall, resulting in more widespread flooding concerns from the
combination of the two sources of water.

The Slight Risk remains in effect for all of coastal North Carolina,
and has been expanded north to include the Hampton Roads area, for
similar combination of tidal and fresh water flooding likely to
impact the urban area there as well. The primary piece of
uncertainty, which is the biggest motivator to keep the flooding
risk at a Slight, is how much instability can work into the system's precipitation north of the low center. The expected lack of
instability, albeit increasing and with convection moving from
higher instability areas to the south into lower instability areas
to the north, supporting persistence, should limit precip rates to
usually more manageable levels, which therefore will limit the
instances of flash flooding, but that is highly dependent on the
low's track and definitely could change.

Wegman
$$
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FOUS30 KWBC 100807
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
407 AM EDT Fri Oct 10 2025

Day 1
Valid 01Z Fri Oct 10 2025 - 12Z Fri Oct 10 2025

...THERE IS A MODERATE RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF ARIZONA AND SOUTHERN UTAH...

...Southwest...

Overall, not much change to the previous forecast, with widespread
showers and storms expected to develop across the region today into
tonight, producing moderate to heavy accumulations, with numerous
flash floods possible.

An amplified upper trough centered along the West Coast will slowly
shift east. Mid level energy embedded within the base of the
trough, along with energy associated with Tropical Cyclone
Priscilla, will converge upon the Southwest today. This energy,
interacting with moisture associated with the tropical system will
support widespread showers and storms, with repeating development
possible. Guidance continues to indicate impressive PW anomalies -
over 5 std dev above normal in some locations according to the GFS.
And while instability may be generally modest across much of the
region, deep saturation through the column will support efficient
rainfall rates, possibly reaching 1-2 in/hr at times.

A Moderate Risk remains in place across central into northern
Arizona, reflecting higher probabilities for amounts over 2 inches
from both the HREF and RRFS. A second Moderate Risk area was added
over portions of southern Utah, including the more vulnerable slot
canyon and national park areas. Overnight hi-res guidance has
trended up across this area, showing storms training from southern
Nevada into the region, with probabilities for amounts over 2
inches increasing. Higher probabilities for similar amounts also
center along the upslope areas of the San Juans. Currently
considered a higher-end Slight, this area may also be considered
for an upgrade later today.

...Southeastern U.S. Coastal Areas...

An area of low pressure will become better organized east of
Florida this period. As the system strengthens, onshore winds
north of the center will begin to direct deeper moisture toward
the coast. However, the overnight hi-res guidance continues to
indicate that the greater instability will remain offshore,
confining the threat for heavy amounts to the immediate coast.
While widespread heavy rains are not expected, coastal flooding
driven by the strong onshore winds, may elevate runoff concerns for
any rains that do fall across the area.

Pereira


Day 2
Valid 12Z Fri Oct 10 2025 - 12Z Sat Oct 11 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
FOUR CORNERS STATES AS WELL AS FOR PORTIONS OF COASTAL NORTH
CAROLINA AND SOUTHEASTERN VIRGINIA...

...Southwest to the Northern Rockies...

Overall, not much change to the previous forecast.

Heavy rain with flash flooding will remain a concern from the
Southwest into the central Rockies, as deep tropical moisture
continues to spread north. While moisture and energy associated
with the remnants of Tropical Cyclone Priscilla will be quickly
lifting north, additional moisture emanating from Tropical Cyclone
Raymond will begin to spread into the Southwest as well. This
combination of moisture and increasing upper level jet support will
likely produce another day of widespread shower and storm
development, albeit a bit further east than the previous day, with
the greater threat for heavy rain and flash flooding centered over
central and southeastern Arizona and over the San Juans. Although
instability may again be limited, the available moisture and lift
may be sufficient to support rainfall rates over 1 in/hr in some locations.

Farther north, moisture will be drawn out ahead of a highly-
amplified upper trough. While rates may be less intense, this
combination of moisture and strong lift may generate showers and
storms that produce localized runoff concerns as far north as
parts of southwestern and central Montana before snow levels begin
to fall late in the period.

...Mid-Atlantic Coast...

There remains uncertainty in the exact track of a low-pressure
system that is forecast to deepen as it moves along the Southeast
and Mid Atlantic coasts this period. What remains more certain is
the heavy rain that is likely to impact portions of eastern North
Carolina and southeastern Virginia. Deep moisture (PWs 1.75-2
inches) along with strong forcing will support heavy rains within
the associated comma-head. The heaviest amounts are expected to
focus across coastal North Carolina, with some deterministic models
indicating that several inches are possible. Similar to the
previous period, a tight east-to-west gradient is likely. However,
as the system intensifies, expect some heavier amounts to spread
further inland than during the previous period. Compound flooding
will remain a concern as coastal flooding generated in part by
strong onshore winds combines with the runoff from the heavy rain.

Pereira


Day 3
Valid 12Z Sat Oct 11 2025 - 12Z Sun Oct 12 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN ARIZONA AND NEW MEXICO, FAR WEST TEXAS, AND ALONG
PARTS OF THE MID ATLANTIC COAST...

....Southeastern Arizona, Southwestern New Mexico, and Far West Texas....

The pattern will remain active for at least a part of the Southwest
as moisture and energy associated with the remnants of Tropical
Cyclone Raymond move into the region. Anomalous moisture along
with large-scale ascent afforded in part by favorable upper jet
forcing will support widespread precipitation and the potential for
heavy amounts from southeastern Arizona to Far West Texas.

...Mid Atlantic and the Northeast...

A coastal low will continue its slow track to the north along the
northern Mid Atlantic this period, with strong onshore winds
driving deeper moisture and the potential for heavy rains north of
the center. The track of the storm and rainfall details remain
uncertain. However, widespread moderate to heavy rain is expected
from the northern Mid Atlantic coast to southern New England, with
coastal flooding likely to compound runoff concerns where heavy
rain does occur.

Pereira
$$
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FOUS30 KWBC 110832
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
432 AM EDT Sat Oct 11 2025

Day 1
Valid 12Z Sat Oct 11 2025 - 12Z Sun Oct 12 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
FOUR CORNERS STATES AS WELL AS FOR PORTIONS OF COASTAL NORTH
CAROLINA AND SOUTHEASTERN VIRGINIA...

...Southwest to the Northern Rockies and High Plains...

An amplified upper trough will move east from the West Coast to
the Rockies. Deep southwesterly flow ahead of the trough will
continue to transport tropical moisture and energy north from the Southwest/Four Corners Region early in the period. The GFS is
showing PW anomalies of 4-5 std dev above normal from the Southwest
into the central Rockies this morning, with anomalies increasing
further to the north into the northern Rockies/High Plains as the
trough continues to shift east later today.

Moisture and energy associated with the remnants of Tropical
Cyclone Priscilla will continue to lift north from the
Southwest/Four Corners region, but residual moisture left in its
wake will maintain significant anomalies from the Southwest up
through Four Corners before a front associated with the upper
trough brings in drier air through the Four Corners by tonight.
However, PW anomalies are expected to remain notably high across
southeastern Arizona and southwestern New Mexico, where moisture
moving out ahead of Tropical Cyclone Raymond is expected to spread
into the region.

Overall, not much change to the previous outlook areas, with a
Slight Risk extending from the Southwest through the Four Corners
into the central Rockies, where moisture and energy associated with
Priscilla are expected to support widespread precipitation,
producing locally heavy amounts early in the period. Both the HREF
and RRFS show high probabilities for accumulations exceeding an
inch covering much of the western Colorado ranges, with high
neighborhood probabilities for amounts exceeding 2 inches centered
over the San Juans. Further to the south, hi-res guidance show
showers and storms firing later today, with repeating development
across portions of southern Arizona and New Mexico. Both the HREF
and RRFS show high probabilities for amounts over 2 inches centered
along the Mogollon Rim into southeastern Arizona and portions of
southwestern New Mexico.

Lastly, across the northern Rockies and High Plains, strong ascent
afforded in part by favorable upper jet forcing, interacting with
the previously noted anomalous moisture plume spreading north, may
be sufficient to produce some locally heavy amounts, with isolated
runoff concerns from eastern Idaho and western Wyoming into parts
of southwestern and central Montana today.

...Coastal Carolinas and Southeastern Virginia...

An area of low pressure now organizing east of Florida will
continue to deepen and track north this morning, before slowing as
it reaches the Carolina coast later today. Strong easterly winds
north of the center will draw deep moisture inland, with heavy rain
likely to impact coastal North Carolina this evening into the
overnight before reaching into southeastern Virginia during the
overnight as well. Models continue to show the potential for
several inches along the North Carolina coast, but with a tight
gradient further inland. Maintained a Slight Risk across coastal
North Carolina into southeastern Virginia, where in addition to
heavy rain, coastal flooding generated by the strong onshore winds
is likely to compound runoff concerns.

Pereira


Day 2
Valid 12Z Sun Oct 12 2025 - 12Z Mon Oct 13 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN ARIZONA AND NEW MEXICO...

...Southern Arizona to West Texas...

Anomalous moisture will remain in place, fortified by moisture
associated with the remnants of Tropical Cyclone Raymond pooling
along the frontal boundary settling into the area. This moisture
interacting with increasing ascent afforded by mid level energy and
favorable upper jet forcing will support additional showers and
storms, with the potential for heavy rain and flash flooding.
Maintained a Slight Risk, but reduced its footprint across the
region. Overall, the 00Z models have trended lighter across the
U.S., with the heaviest amounts focused south of the U.S.-Mex
border. There still remains a decent signal for at least locally
heavy amounts to develop, so a Slight Risk was maintained across
portions of southeastern Arizona into far southwestern New Mexico,
with a Marginal Risk extending farther east into West Texas.

...Mid Atlantic Coast to Southern New England...

Models continue to differ on the details on how the low pressure
along the East Coast will evolve this period. The general consensus
of the models shows an area of low pressure lingering and weakening
over the Mid Atlantic, as a second low begins to develop along the
Northeast Coast as its associated frontal system interacts with a
northern stream low becoming cutoff over the Northeast. The models
however differ on the amplitude and track of the system, lowering
confidence in the precipitation forecast over the Northeast.
Regardless of development, easterly winds will spread at least some
moderate to locally heavy amounts from the northern Mid Atlantic
coast northward into southern New England, with coastal flooding
remaining a compounding concern. Given the uncertainty, with
several models keeping heavy amounts offshore, opted to remove the
Slight Risk for now. However, should the 00Z ECMWF be the start of
a trend toward a more amplified/westerly solution, a Slight Risk
may be reintroduced.

Pereira


Day 3
Valid 12Z Mon Oct 13 2025 - 12Z Tue Oct 14 2025

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL ACROSS PORTIONS OF SOUTHEASTERN ARIZONA, SOUTHWESTERN NEW MEXICO, AND SOUTHERN
COLORADO...

...Southwest to the Central Rockies...

Backing flow ahead of a deep low dropping south into northern
California will draw lingering anomalous moisture over the
Southwest back to the north into the central Rockies. This moisture
interacting with favorable mid to upper level forcing will generate
additional showers and storms, with guidance indicating an elevated
chance for locally heavy amounts and flash flooding concerns over
portions of southeastern Arizona, southwestern New Mexico, and the
San Juan Mountains.

...Northern and Central California....

Models are in generally good agreement showing an anonymously deep
upper developing and dropping south along the West Coast from the
Pacific Northwest to Northern California this period. Moisture with
the system will be relatively modest initially, but enough to
raise moisture anomalies to over a std dev above normal along its
axis of strong onshore flow. This along with strong forcing may be
sufficient to produce locally heavy amounts, with isolated runoff
concerns, especially in the upslope regions of the coastal ranges
and the Sierra foothills.

....Northeast...

Plenty of questions remain as to how the low developing along the
Northeast coast will continue to evolve, but most agree on at least
a localized threat for heavy rain centered along the southeastern
New England coast continuing into the period.

Pereira
$$
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FOUS30 KWBC 120806
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
406 AM EDT Sun Oct 12 2025

Day 1
Valid 12Z Sun Oct 12 2025 - 12Z Mon Oct 13 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHERN ARIZONA AND NEW MEXICO...

...Southwest...
Deep moisture, fortified with the remnants of Tropical Cyclone
Raymond, will remain in place over portions of southern Arizona and
New Mexico. This morning's mesoanalysis shows PWs of 1.25-1.6
inches (3-4 std dev above normal) covering much of region. This
moisture along with increasing large-scale ascent, provided by an
approaching upper trough, will support another day of widespread
showers and storms capable of producing moderate to heavy amounts.
Maintained a Slight Risk covering much of southern Arizona and a
small portion of southwestern New Mexico. Both the HREF and RRFS
neighborhood probabilities indicate locally heavy amounts
exceeding 2 inches are likely within this region, with some
potential for amounts over 3 inches, especially across parts of
southern Arizona.

...Eastern Southern Carolina and Southeastern North Carolina...

The initial low of what is expected to evolve into a two feature
system is forecast to linger along the coast in the vicinity of the
North and South Carolina border today. Deeper moisture will remain
as well, with many of the 00Z models, including the globals,
showing a notable signal for locally heavy amounts developing later
today. While instability will be limited, deep saturation through
the column, and tall, skinny CAPEs are expected to support very
efficient rains, promoting heavy amounts. Both the HREF and RRFS
showing high probabilities for additional amounts over 3 inches
today across parts of the region. These amounts may raise runoff
concerns, especially for those areas where significant rains have
already occurred. Therefore a Marginal Risk was introduced for
areas where the hi-res ensembles indicate the heaviest amounts are
most likely to fall.

...Northern Mid Atlantic to Southern New England Coasts...

North of its parent, a secondary, triple-point low is forecast to
develop near the northern Mid Atlantic coast. There remains some
model uncertainty regarding if and to what degree this low will
become the dominant surface feature. Despite the differences,
there is broad agreement that strong, low level easterly winds, in
combination with strong mid-to-upper level forcing, will support
widespread precipitation from the northern Mid Atlantic coastal
region to central New England, with heavy amounts expected along
the coast. These heavy rains may compound what are likely to be
poor ground conditions attributed to ongoing coastal flooding.

Pereira


Day 2
Valid 12Z Mon Oct 13 2025 - 12Z Tue Oct 14 2025

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL ACROSS PORTIONS OF SOUTHEASTERN ARIZONA, SOUTHWESTERN NEW MEXICO, AND SOUTHERN COLORADO...

...Southwest to the Central Rockies...

Lingering deep moisture over southern Arizona and New Mexico will
be drawn north ahead of an upper trough amplifying over California.
This moisture along with the broad-scale ascent afforded by the
upper trough will support one more day of showers and storms across
the Southwest, but this time shifting a bit further east while
extending north across New Mexico into the central Rockies. With
drier air working into southwestern Arizona, the potential for
heavy rain and the threat for flash flooding will become more
limited across that area. However, further to the north and east, a
Slight Risk was maintained along eastern portions of the Mogollon
Rim into southeastern Arizona and southwestern New Mexico. There
remains a notable signal for additional moderate to locally heavy
amounts across that area. Also remaining is a Slight Risk in a
portion of the San Juan Mountains, where models show deep
persistent southerly winds, along with favorable upper forcing,
supporting heavy totals as well.

...Northern and Central California....

Models remain in generally good agreement, showing an anonymously
deep upper developing and dropping south along the West Coast from
the Pacific Northwest to Northern California this period. Moisture
with this system will be relatively modest initially, but enough
to raise moisture anomalies to 1-2 std dev above normal along its
axis of strong onshore flow. This along with strong forcing may be
sufficient to produce locally heavy amounts, with isolated runoff
concerns, especially in the upslope regions of the coastal ranges
and the Sierra foothills below the snow line.

....Northeast...

Questions remain as to how the low developing along the Northeast
coast will continue to evolve, but most agree on at least a
localized threat for heavy rain spreading north from southern New
England up along the coast to areas perhaps as far north as coastal
Maine. Given the uncertainty, kept the Marginal Risk centered to
the area where the GEFS and ECENS both indicate that amounts
exceeding an inch are most likely.

Pereira


Day 3
Valid 12Z Tue Oct 14 2025 - 12Z Wed Oct 15 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL OVER PORTIONS OF
CENTRAL TO SOUTHERN CALIFORNIA, NEW MEXICO, AND WEST TEXAS...

...Central to Southern California...

A deep upper low will continue to dig south early in the period
before turning east across California into the Great Basin this
period. Before turning inland, this system will support an ongoing
threat for heavy precipitation, with the focus shifting south along
with its associated axis of deep onshore flow across Southern
California into the southern Sierra Nevada. A Marginal Risk was
drawn south along the Southern California Transverse Ranges, where
0.75-1 inch PWs interacting with favorable upper jet dynamics and
orographic ascent are expected to support rainfall amounts of 1-2
inches along the favored terrain. These amounts may produce
isolated runoff concerns, especially over vulnerable burn scar
areas. A Marginal Risk was also maintained further to the northeast
along the southern Sierra foothills, where similar amounts are
expected below the snowline.

...New Mexico and West Texas...

As drier air continues to spread east across Arizona into eastern
New Mexico, PWs anomalies will remain high across portions of
central New Mexico and West Texas where strengthening low level
easterly winds will add to the lingering moisture. With the
increase in moisture, the GFS shows PW anomalies remaining over 3
std dev above normal across much of the highlighted areas. This
along with daytime heating will support additional shower and
thunderstorm development, with some potential for locally heavy
amounts and isolated runoff concerns.

Pereira
$$
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FOUS30 KWBC 130754
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
354 AM EDT Mon Oct 13 2025

Day 1
Valid 12Z Mon Oct 13 2025 - 12Z Tue Oct 14 2025

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL ACROSS PORTIONS OF SOUTHEASTERN ARIZONA, SOUTHWESTERN NEW MEXICO, AND SOUTHERN COLORADO...

...Southwest to the Central Rockies...

Elevated moisture running between 2-4 deviations above normal will
remain situated across the Four Corners into the Central Rockies
down through the Southwest CONUS with roots persistent from the
tropical flux associated with now deceased tropical cyclone
Raymond. The persistence in the longwave pattern has allowed for a
continuous onslaught of heavy convective threats across the Desert
Southwest with a large amount of flash flood warnings tied to the
efficient rainfall processes exhibited given the supportive
atmospheric profile. For at least one more period, another round of
heavy precip will focus across portions of AZ/NM up into the San
Juans and adjacent Rockies of CO thanks to the flow actually
becoming even more meridional in-leiu of a buckling upper jet
pattern across the west coast stemming from a digging powerful
shortwave meandering down from the Pacific Northwest (More on this
setup below). As of now, there is a consistent signal in the hi-res
means for scattered heavy convective threats situated along the
eastern half of the Mogollon Rim into NM with a secondary maxima
situated over the San Juans where persistent upslope flow and mid-
level perturbations will enhance rainfall concerns within the
terrain for a third consecutive day.

00z HREF EAS probs for >1" are running high (>60%) for both the
areas mentioned above, plus >2" signals across the San Juans
maintain a strong 50-70% output meaning heavy rain prospects are
increasingly certain in the period. The one caveat to a higher
threat is the general lack of sufficient rates that would promote a
greater flash flood concern, especially one that carries more
significant impacts. Locally impactful outcomes are still plausible
considering some of the antecedent conditions leading into the
setup, so it's not out of the question some considerable flash
flood prospects could materialize in areas outlined in the SLGT
risk. Overall, this setup is conducive for at least scattered flash
flood potential leading to a general continuity of the SLGT from
previous forecasts with some adjustments based on the latest prob fields.

...California....

Current WV satellite and UA analysis indicates a powerful closed
ULL situated over the Olympics of Washington state with an
anticipated trajectory down the Pacific coast before it finally
loses latitude near Central CA before beginning to pivot inland.
During the forecast upper evolution, a strong south-southwest push
of Pacific moisture will favor an increase in regional PWAT
advection pressing inland across CA through the course of the D1.
The latitudinal push will allow for a persistent onshore component
within the coastal terrain from northwest CA down into the
Transverse Range of Southern CA towards the back end of the
forecast cycle. This will allow for 6-12 hr periods of heavy
rain potential within the confines of those coastal terrain
elements leading to isolated flash flood prospects as the setup
evolves. As of this time, the greatest threats for flash flooding
will be within those coastal terrain proxy's, however the inland
push of slightly anomalous moisture will also produce an element of
heavy rainfall in the Sierra Foothills, especially for the upslope
regions of the central and southern Sierra below 7000ft MSL. These
areas could see impacts from complex drainage within the steep
terrain situated against the higher elevations just east that will
be encountering the first true winter event of the season at the
same juncture. Rates will be relatively capped as MUCAPE fields are
generally forecast to be more benign compared to other instances
we've had in the past. The best MUCAPE signatures are actually
aligned with the Transverse Range and northern Peninsular Range of
southern CA, an area that is likely the most prone for flash flood
potential due to the litany of burn scar remnants present over the area.

Trends the past 12-24 hrs. now position the flow to be generally
orthogonal to the terrain those locations towards the end of the
forecast cycle, a setup conducive for persistent heavy rainfall
anchored over the same areas for longer periods of time. Despite
the lack of enhanced rates, enough instability and orographic
forcing could lead to rates exceeding 1"/hr at times, more than
sufficient for flash flood concerns to arise right near the final 6
hr. period in the D1. The previous forecast was relatively
unchanged north of the Transverse Range, but with the deeper
meridional inflection in the mean trough, the threat for flash
flooding across the southern CA terrain has sped up in time, thus a
MRGL extension into the Ranges northwest and north of Los Angeles
were implemented to reflect the latest trends. This will be a time
frame to monitor for any targeted upgrades if guidance allows.

Kleebauer


Day 2
Valid 12Z Tue Oct 14 2025 - 12Z Wed Oct 15 2025

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL OVER PORTIONS OF
SOUTHERN CALIFORNIA...

...Central to Southern California...

Our western disturbance will continue its progression slowly inland
with a steady south-southwesterly component situated over the
terrain of southern CA. Expect a continuance from the D1 to bleed
into the first half of D2 with heavy rainfall aligned within the
eastern Transverse Range and the northern Peninsular Range to the
north and northeast of Los Angeles. PWAT anomalies on the order of
1-2 deviations above normal are sufficient for a deep layer
moisture regime capable for heavy rainfall rates between 0.5-1"/hr
with a chance for a few stronger cores to exceed 1"/hr, a signal
more than capable of producing flash flooding in-of the area most
susceptible given the burn scar remnants positioned in the
Peninsular Range. Additional totals of 1-3" are forecast with
locally higher possible in those areas northeast of Los Angeles in
the terrain. Totals for the event will run between 1-4", plentiful
over a span of 12-24 hrs. to cause issues in what is a sensitive
locale for flash flooding and debris flow. The previous SLGT risk
was linked together and spans the eastern Transverse into the
northern Peninsular Range. MRGL risk is in place surrounding,
including an extension into parts of the Central Valley and
adjacent Sierra Foothills as locally heavy rainfall is still
forecast through the first 6-12 hrs. of the period which could spur
some isolated flash flood signals.

...New Mexico and West Texas...

Remnant elevated moisture across far west TX into NM within a
persistent axis of diffluent flow will yield a period of scattered thunderstorms over the two areas leading to isolated flash flood
concerns, mainly in urban zones and over the complex terrain
aligned from the Sacramento's up into the Sangre de Cristos. Totals
are not very appreciable at this juncture, but environmental
conditions still support some heavier rainfall prospects over areas
that will have seen a decent amount of rain leading in. Combination
of antecedent conditions and additional rainfall place the threat
inside the MRGL risk threshold leading to general continuity from
previous forecast.

Kleebauer


Day 3
Valid 12Z Wed Oct 15 2025 - 12Z Thu Oct 16 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL OVER PORTIONS
OF THE CENTRAL AND SOUTHERN ROCKIES...

...Rockies...

Longwave pattern out west will continue to evolve with upstream
troughing pushing east-northeast leading to a final prospect of
isolated to scattered convection over the terrain of the central
and southern Rockies. A lot of the threat stems from RER
positioning with a broad upper jet aligned over the Mountain West
with an extension into the High Plains by the end of the forecast
cycle. The main areas of concern will likely be in those complex
terrain locations in-of the Sangre de Cristos, San Juans, and down
near the Sacramento's. These areas will all have either very wet
antecedent soil moisture that would promote easier run off
capabilities, or burn scar remnants that maintain a posture for
localized flash flood opportunities with any rates >0.5"/hr. This
is still feasible with PWATs remaining ~2 deviations above normal
in this zone when assessing the latest NAEFS output. A MRGL risk
remains in place over these areas of the central and southern
Rockies as a result.

Kleebauer
$$
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FOUS30 KWBC 140740
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
340 AM EDT Tue Oct 14 2025

Day 1
Valid 12Z Tue Oct 14 2025 - 12Z Wed Oct 15 2025

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL OVER PORTIONS OF
SOUTHERN CALIFORNIA AND NEW MEXICO...

...Central to Southern California...

Current UA analysis and WV satellite imagery pins the powerful ULL
off the northern CA coast, situated just west of San Francisco Bay.
The forecast trajectory will place the low center off the the
central CA coast by tomorrow morning with a reprieve in lost
latitude as the low center will mostly come to a stop and begin a
slow pivot inland. The proxy of the ULL will create a strong
south-southwest fetch off the Pacific around the base of the ULL
creating a prolonged period of orthogonal upslope flow in-of the
Transverse and Peninsular Ranges of southern CA. The threat will be
ongoing at the very beginning of the forecast cycle as the effects
of heavy rainfall will bleed from the current D1 into this new D1
time period. Consensus in pretty much all guidance maintains a high
confidence posture of locally significant rainfall across those
coastal terrain areas, especially over the eastern Transverse and
northern Peninsular Ranges to the north and northeast of Los
Angeles. The predominant flow is textbook for upslope enhancement
within the confines of those areas which historically can lead to
scattered bouts of flash flooding and localized debris flows. PWATs
will hover around 2 deviations above normal with a small axis of
MUCAPE located right near the coast to just inland over the
terrain. Despite the signal reflected being between 200-500 J/kg of
CAPE, this is likely sufficient to push rates over the terrain to
~1"/hr with perhaps a few stronger cores exhibiting higher rates
for short periods of time.

Considering the multitude of burn scar remnants and just complex
terrain funneling over the Transverse and Peninsular Ranges, this
setup is more than conducive for scattered flash flood concerns, at
a minimum. 00z HREF neighborhood probs for >3" of total precip in
the D1 is between 60-90% over that areas in the eastern Transverse
and northern Peninsular Ranges, overlapping some of the more prone
burn scar areas that remain over these locations. The good news in
the setup is the progression of the heavy rainfall will not be an
all day affair, but still will cover the period between 12-21z
Tuesday with some rainfall encountered just prior to the new D1.
This allowed for a general maintenance of the SLGT risk in place
over the region with a minor adjustment to expand on the southern
flank into the Peninsular Range as models hint at a secondary
maxima situated just northeast of San Diego within the terrain
aligned over western Riverside county.

...New Mexico and West Texas...

Persistence in the general longwave pattern closer to the divide
will create yet another active period for scattered to widespread
convective impacts during the day on Tuesday. As of this time,
elevated moisture on the order of 2-3 deviations above normal,
according to the latest NAEFS signal an environment conducive for
locally heavy rainfall, especially in-of terrain elements that can
provide local enhancement given the persistence of southern flow
overhead. A stout mid-level ridge sits over the Southern Plains
allowing for a channel on the western flank of the ridge to
coincide with the prevailing easterly flank of the broad upper
trough centered over the Western U.S. The latest trend within
guidance is to advect a relatively stout mid-level shortwave out of
Chihuahua late-Tuesday afternoon and evening with a steady south to
north progression as we move through the second half of the
forecast period. The signal is reflected in both the 500mb
vorticity panels, and is defined in the 700mb wind field leading to
higher confidence in the potential of this shortwave advection
scheme over the region.

Recent HREF blended mean QPF has jumped from run to run with a
relative max centered over the Sangre de Cristos of northern NM
with some smaller maxima positioned over the Sacramento Mtns. These
two areas are still fairly sensitive considering multiple burn
scar remnants, including a few very sensitive grounds based within
both terrain features. Totals of 1-2" with locally higher are
forecast within individual deterministic leading to an uptick in
neighborhood probs for >2" now upwards of 60-80% in the
Sacramento's and 35-50% over the Sangre de Cristos. This is more
than enough to spur issues over these two specific areas leading to
an upgrade to a SLGT risk now centered over south-central to
north-central NM. The threat is a little less daunting over areas
outside the terrain, but there could still be issues outside the
higher elevations due to drainage and heavier cells drifting off
the terrain into the adjacent valleys. This is the reasoning for
maintaining the SLGT over the valleys between the two ranges.

Kleebauer


Day 2
Valid 12Z Wed Oct 15 2025 - 12Z Thu Oct 16 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL OVER PORTIONS
OF THE CENTRAL AND SOUTHERN ROCKIES...

...Rockies...

The evolution of the longwave pattern across the Western CONUS will
lead to the development of a surface low over the Inter-Mountain
West with a trailing cold front anticipated to move west to east
over the Four Corners into the Continental Divide. The combination
of continued ascent within the RER of a vacating jet streak to the
north and the frontal approach will lead to one last instance of
organized precip within the San Juans down into the Sangre de
Cristos. Considering the nature of the pattern bookending quite an
active stretch within the aforementioned areas, the threat for
flash flooding will lie within the MRGL risk threshold despite the
lack of stronger instability that tends to necessitate a greater
flash flood potential. Antecedent conditions will trend very wet
overall leading to lower FFG's across the terrain of northern NM
into southwestern CO. Totals within guidance are currently running
between 0.5-1" with some locally higher amounts based in the
individual deterministic. The greatest threat for higher totals
lies within the San Juans, an area that has been the benefactor of
significant rainfall totals the past 4 days. This will likely be
the greatest area of focus for the setup, albeit a threat that will
be closer to a 6-8 hr. window as the front approaches. The previous
MRGL risk was generally maintained, but trimmed up the southern
edge as model trends point to limited potential for heavier
rainfall south of the Sangre de Cristos in northern NM.

Kleebauer


Day 3
Valid 12Z Thu Oct 16 2025 - 12Z Fri Oct 17 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Kleebauer
$$
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FOUS30 KWBC 150719
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
319 AM EDT Wed Oct 15 2025

Day 1
Valid 12Z Wed Oct 15 2025 - 12Z Thu Oct 16 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
COLORADO AND NORTHERN NEW MEXICO...

A large mid/upper wave centered across Nevada at 12Z Wednesday will
migrate eastward during the forecast period, spreading height falls
across the central and southern Rockies. As this occurs, cooling
aloft and surface heating will foster development of a few showers
and thunderstorms across southern Colorado and northern New Mexico
especially during the afternoon and evening hours. Point forecast
soundings across the region depict fast storm motions (30-50
knots) with any developing convection, although steep lapse rates
aloft and 0.5-0.75 inch PW both suggest potential for brief heavy
rainfall especially where any backbuilding can materialize. Wet
antecedent conditions and very high streamflows (per the USGS Water
Dashboard) are suggestive of ground conditions that are readily
supportive of excessive runoff due to poor drainage. Additionally,
a few burn scars across the region could support local excessive
runoff at times. Areas of 1-2 inch rainfall totals are possible -
especially in upslope and terrain-favored areas. Isolated flash
flooding is possible in this regime.

Cook


Day 2
Valid 12Z Thu Oct 16 2025 - 12Z Fri Oct 17 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ALONG MUCH OF THE MONTANA/NORTH DAKOTA BORDER...

Strengthening mid-latitude cyclone will traverse the Northern High
Plains by Thursday afternoon and beyond with a developing closed
mid-level vorticity center propagating over eastern MT to the MT/ND
border. The subsequent evolution will lead to a period of moderate
to heavy rainfall across the above areas with a prominent
deformation axis anticipated to setup along the MT/ND border. At
this juncture, instability will be lacking from a thermodynamic
sense, however the dynamical forcing and prolonged period of
enhancement with the axis of deformation will likely spur a
widespread area of moderate to heavy rainfall capable of low-end
flash flood concerns. These concerns will be suited mainly over
those urbanized zones and any low-water crossing. Totals area
expected to be a widespread 1-2" of rainfall with some localized
totals >2", likely over western and northwestern ND as the heaviest
rain will hang on there given the proxy of the surface low
progression and positioning of the axis of deformation. A MRGL risk
was maintained with a small expansion south to account for the
latest QPF trends.

Kleebauer


Day 3
Valid 12Z Fri Oct 17 2025 - 12Z Sat Oct 18 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Kleebauer
$$
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FOUS30 KWBC 160806
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
406 AM EDT Thu Oct 16 2025

Day 1
Valid 12Z Thu Oct 16 2025 - 12Z Fri Oct 17 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE NORTHERN HIGH PLAINS...

Strengthening mid-latitude cyclone will traverse the Northern High
Plains by Thursday afternoon and beyond with a developing closed
mid-level vorticity center propagating over eastern MT to the MT/ND
border later Thursday night. The subsequent evolution will lead to
a period of moderate to heavy rainfall across the above areas with
a prominent deformation axis (deepening TROWAL zone) anticipated
to setup along the MT/ND border. At this juncture, instability will
be lacking from a thermodynamic sense, however the dynamical
forcing and prolonged period of enhancement with the axis of
deformation will likely spur a widespread area of moderate to heavy
rainfall capable of low-end flash flood concerns. These concerns
will be suited mainly over those urbanized zones and any low-water
crossing. Totals area expected to be a widespread 1-2" of rainfall
with some localized totals >2", likely over parts of eastern MT
into western and northwestern ND, as the heaviest rain will hang
on there given the proxy of the surface low progression and
positioning of the axis of deformation. A MRGL risk was maintained
with a small expansion south and east to account for the latest
QPF trends.

Hurley


Day 2
Valid 12Z Fri Oct 17 2025 - 12Z Sat Oct 18 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Hurley


Day 3
Valid 12Z Sat Oct 18 2025 - 12Z Sun Oct 19 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PARTS OF THE
MID-SOUTH AND LOWER OHIO VALLEY...

By the beginning of Day 3 (12Z Sat), the southern stream shortwave
traversing the Southern Plains will begin to merge with the
northern stream shortwave digging into the Central Plains. As this
occurs, by the end of the period (12Z Sun) there will be a
strengthening upper level jet streak rounding the trough base, with
a fairly vigorous and sizable accompanying vort center across the
Lower MO and Mid MS Valley. As the upper shortwaves phase, the
guidance remains consistent with the uptick in low-level moisture
transport across the Mid South into the Lower OH Valley (confluence
of the MS and OH Rivers). The 00Z GEFS in fact shows 850 mb
moisture flux between 3-3.5 standard deviations above normal over
the Slight Risk area, along an axis of TPW values between 1.7-1.9".

Meanwhile, deep-layer instability, while not overly robust (MUCAPEs
500-1000 J/Kg per the 00Z GFS), will be sufficient for intense
short-term rainfall rates considering the degree of synoptic
forcing and available deep moisture. The main inhibitor to the
excessive rainfall threat is the likelihood that the upper trough
and associated surface cold front will become more progressive with
time later in the period (Sunday night). Nevertheless, the setup
continues to align with the expectations of a low-end Slight ERO
Risk, as supported by the latest CSU ERO first-guess fields (UFVS
verified) over an area where the current 3 hourly FFG is 2-2.5
inches.

Hurley
$$
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FOUS30 KWBC 161930
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
330 PM EDT Thu Oct 16 2025

Day 1
Valid 16Z Thu Oct 16 2025 - 12Z Fri Oct 17 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE NORTHERN HIGH PLAINS...

16z update: Forecast remains on track and no sizable adjustments
were required.

A line of scattered thunderstorms along a stationary front with
possible short-term training from SSW to NNE exists across the
Central High Plains of NW KS into the Sand Hills of NEB. Localized
1-2" totals are possible given 500-750 J/kg of CAPE and flux
confluence of 30-40kts of 1-1.25" total Pwats. However, rates will
generally be around .75-1"/hr and given soil conditions, rains are
likely to be mainly beneficial rains than hazardous. As such, there
is a non-zero risk of isolated flooding, but remains at a sub-
Marginal Risk category.

Gallina


~~~~~Prior Discussion~~~~~
Strengthening mid-latitude cyclone will traverse the Northern High
Plains by Thursday afternoon and beyond with a developing closed
mid-level vorticity center propagating over eastern MT to the MT/ND
border later Thursday night. The subsequent evolution will lead to
a period of moderate to heavy rainfall across the above areas with
a prominent deformation axis (deepening TROWAL zone) anticipated
to setup along the MT/ND border. At this juncture, instability will
be lacking from a thermodynamic sense, however the dynamical
forcing and prolonged period of enhancement with the axis of
deformation will likely spur a widespread area of moderate to heavy
rainfall capable of low-end flash flood concerns. These concerns
will be suited mainly over those urbanized zones and any low-water
crossing. Totals area expected to be a widespread 1-2" of rainfall
with some localized totals >2", likely over parts of eastern MT
into western and northwestern ND, as the heaviest rain will hang on
there given the proxy of the surface low progression and
positioning of the axis of deformation. A MRGL risk was maintained
with a small expansion south and east to account for the latest QPF
trends.

Hurley


Day 2
Valid 12Z Fri Oct 17 2025 - 12Z Sat Oct 18 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Gallina


Day 3
Valid 12Z Sat Oct 18 2025 - 12Z Sun Oct 19 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM NORTHERN
ARKANSAS TO NORTHERN INDIANA...

21z update:
12z guidance trends depict a tightening of the two phasing
shortwave features; with the northern stream digging a tad faster
and the southern stream slowing and lifting northward. As such the
initial rounding jet streak appears to be broadening and increasing
overall diffluence across the Central MS Valley; further enhancing
low level confluent flow toward 45-50kts and generally supporting
of increased duration of enhanced flux within the training
convective environment from the eastern Ozark Plateau across
central IL toward L.P. of MI. The higher flux, slightly higher
CAPEs to 500-1500 J/kg, and solid right entrance ascent and general
diffluence while maintaining a parallel mean cell motion to the
mean wind supporting SSW to NNE training along and downstream of
the surface wave. As such, guidance has seen an increase in overall
totals toward 2-3" though localized totals to 4"+. Instability
reduces fairly quickly through the late afternoon, but the dynamics
remain strong to have enhanced rainfall totals into the central Great Lakes.

South of the base of the northern stream trof, cold front should be
more progressive, dropping southeast. Deeper moisture pool and
instability of 1000-2000 J/kg will allow for stronger/broader
updrafts with higher rainfall intensity, but steering should
limit duration with only exception to any right moving rotating
updrafts that could locally reduce forward speed while increasing
moisture flux convergence in speed and directional confluence. As
such, narrower streets of enhanced rainfall totals are more likely
than in the deformation zone further north. Along with higher FFG
values, a broader Marginal Risk is preferred at this time/cycle.

Gallina

~~~~Prior Discussion~~~~
By the beginning of Day 3 (12Z Sat), the southern stream shortwave
traversing the Southern Plains will begin to merge with the
northern stream shortwave digging into the Central Plains. As this
occurs, by the end of the period (12Z Sun) there will be a
strengthening upper level jet streak rounding the trough base, with
a fairly vigorous and sizable accompanying vort center across the
Lower MO and Mid MS Valley. As the upper shortwaves phase, the
guidance remains consistent with the uptick in low-level moisture
transport across the Mid South into the Lower OH Valley (confluence
of the MS and OH Rivers). The 00Z GEFS in fact shows 850 mb
moisture flux between 3-3.5 standard deviations above normal over
the Slight Risk area, along an axis of TPW values between 1.7-1.9".

Meanwhile, deep-layer instability, while not overly robust (MUCAPEs
500-1000 J/Kg per the 00Z GFS), will be sufficient for intense
short-term rainfall rates considering the degree of synoptic
forcing and available deep moisture. The main inhibitor to the
excessive rainfall threat is the likelihood that the upper trough
and associated surface cold front will become more progressive with
time later in the period (Sunday night). Nevertheless, the setup
continues to align with the expectations of a low-end Slight ERO
Risk, as supported by the latest CSU ERO first-guess fields (UFVS
verified) over an area where the current 3 hourly FFG is 2-2.5
inches.

Hurley
$$
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FOUS30 KWBC 170757
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
357 AM EDT Fri Oct 17 2025

Day 1
Valid 12Z Fri Oct 17 2025 - 12Z Sat Oct 18 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Oravec


Day 2
Valid 12Z Sat Oct 18 2025 - 12Z Sun Oct 19 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM NORTHWEST
ARKANSAS, ACROSS SOUTHERN MISSOURI INTO SOUTHERN ILLINOIS...

The latest models remain in good agreement on the overall
sharpening of the mid to upper level trof across the mid section of
the nation Saturday into early Sunday. Well defined upper difluence
likely between the northern stream vort moving east southeast
across the Central Plains and the southern stream vort moving east
northeast across the Southern Plains. PW values will increase to 1
to 2+ standard deviations above the mean in this broad upper
diffluent axis from eastern portions of the Southern Plains,
northeastward into the Mid MS Valley and Great Lakes, along and
ahead of the associated eastward moving frontal boundary. Model
consensus is for a broad area of moderate to heavy rainfall amounts
in this axis. All of this region has been very dry with relative
soil moisture low, low stream flows and subsequently FFG values
very high, which will be a detriment to widespread runoff issues.
The previous slight risk area was shrunk considerably, focusing it
where the HREF and RRFS means show higher probabilities for 1 and
2"+ amounts in the 12 hour period from 12Z Sat Oct 18 to 00Z Sun
Oct 19 from northwest AR, across southern MO into southern IL. This
region also corresponds to where the relative soil moisture is not
as low as points farther to the northeast and southwest, although
overall, still low. There may be a period of training of cells in
the slight risk area during the first half of the day 2 period,
before the convection begins to accelerate to the east and
southeast during the second half of day 2. The previous marginal
risk area was also decreased significantly, narrowing the eastern
extent through the OH and TN Valleys.

Oravec


Day 3
Valid 12Z Sun Oct 19 2025 - 12Z Mon Oct 20 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE EASTERN
GREAT LAKES INTO THE CENTRAL APPALACHIANS...

The amplifying mid to upper level trof across the mid section of
the nation day 2, will continue to accelerate eastward day 3,
becoming increasingly negatively tilted as it moves through the OH
Valley, Central Appalachians, Mid- Atlantic and eastern Lakes. The
fast eastward movement will continue to be a limiting factor for
very heavy rainfall amounts and any widespread runoff issues. While
FFG values are much lower across the eastern Lakes into the Upper
OH Valley and Central Appalachians than areas farther south and
west during the day 2 period, the aforementioned progressive
nature of the day 3 system should preclude most areas exceeding
FFG values. No changes made to the previous marginal risk area from
the eastern Lakes, south into the Upper OH Valley and Central
Appalachians.

Oravec
$$
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FOUS30 KWBC 190736
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
336 AM EDT Sun Oct 19 2025

Day 1
Valid 12Z Sun Oct 19 2025 - 12Z Mon Oct 20 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

We decided to remove the previous marginal risk area across far
southeast Ohio into West Virginia and a small portion of southwest
PA after viewing the latest HREF and RRFS probabilities. No changes
to the thinking that the frontal/pre-frontal precip expected to
push eastward across the Lower Lakes/Upper OH Valley/Central
Appalachians area Sunday will be very progressive. This and limited
instability will likely keep hourly rates under the FFG values that
are generally 1-2"/hr. The greatest rainfall rates likely with the
initial line of rain pushing eastward late morning/early
afternoon. With this initial line, the HREF and RRFS mean
probabilities of 1"+/hr rains are nearly zero.

Oravec


Day 2
Valid 12Z Mon Oct 20 2025 - 12Z Tue Oct 21 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS NORTHERN
NEW YORK STATE INTO WESTERN NEW ENGLAND...

The upper trof swinging through the Lower Lakes/OH Valley/Central
Appalachians day 1 will become more negatively tilted, closing off
an upper center day 2 across the northern Mid-Atlantic into
Northern NY State and northern New England. 850-700 mb moisture
flux will will remain anomalous, 2 to 4 standard deviations above
the mean, ahead of this closing off system into the terrain of
northern NY State and western New England. The RRFS and HREF 1"+/hr probabilities do increase Monday morning over western New England
into northern NY State, peaking at 15-30% in the marginal risk
area. There is still spread in the model qpfs, but consensus for
widespread moderate to heavy rainfall potential. Overall, no
significant changes to the previous marginal risk area across
northern NY State into western New England, with it still aligned
with the latest WPC qpf maximum from northern NY State, across much
of VT, western MA, north-central NH into western ME.

Oravec


Day 3
Valid 12Z Tue Oct 21 2025 - 12Z Wed Oct 22 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Oravec
$$
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FOUS30 KWBC 200742
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
342 AM EDT Mon Oct 20 2025

Day 1
Valid 12Z Mon Oct 20 2025 - 12Z Tue Oct 21 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS INTERIOR
NEW ENGLAND...

Anomalous PW (1.5-2.5 standard deviations above the mean) and
850-700 mb moisture flux(3-5 standard deviations above the mean)
values will accompany the strong cold/occluded frontal boundary
that will sweep northeastward through New England Monday. Hi res
models all show an uptick in hourly rainfall amounts along and
ahead of this front beginning shortly after 1200 UTC. Both the HREF
and RRFS neighborhood probabilities are high for hourly totals in
the .50-1" range as the front sweeps northeastward on Monday.
Concerns continue for isolated runoff issues where the anomalous
850-700 mb moisture flux will produce strong upslope flow across
much of VT, NH and into western ME. Across these areas both the
HREF and RRFS neighborhood probabilities are high for 2"+ total
amounts during day 1. Overall, only some minor changes made to the
previous marginal risk area.

Oravec

Day 2
Valid 12Z Tue Oct 21 2025 - 12Z Wed Oct 22 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Oravec

Day 3
Valid 12Z Wed Oct 22 2025 - 12Z Thu Oct 23 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Oravec

$$
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FOUS30 KWBC 230745
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
345 AM EDT Thu Oct 23 2025

Day 1
Valid 12Z Thu Oct 23 2025 - 12Z Fri Oct 24 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS...

...Southern Plains...
At the start of the forecast period, 23.12z, a southern stream
fairly concentric/symmetric mid-level cyclone continues to advance
across the Four Corners region of the Southwest. The low will
continue to consolidate and deepen slightly throughout the day as a
stronger (90+ kt) jet streak rounds the base toward 24.00z
broadening across the southern High Plains providing strengthening
left exit and diffluent larger scale ascent across the Southern
Plains thereafter.

The low levels were already responding with and open Western Gulf
return stream of enhanced theta-E air northward across central
Texas toward the Big Country and Red River Valley. As the
divergence increases aloft, the LLJ responds with 850mb increase
from 15-20kts toward 30-35kts with broad veering increasing low
level confluence/convergence after dark. Combine this with cross
northern Mexico sub-tropical moisture into the 700-500mb layer and
overall total PWat values increase from 1-1.25" toward 1.5" by late
evening. Modest lapse rates with support MUCAPE 1000-1500 J/kg and
the strong WAA/isentropic ascent across the frontal zone should
allow for scattered elevated convective activity across southern KS
and central OK throughout the evening. Hi-Res CAMs suggest there
may be some back-building potential given the strengthening LLJ
and with deep-layer flow, some short-term training may exist.

As the night progresses, core of highest theta-E, West Gulf
moisture reaches the surface front. Moisture flux convergence
increases and half of the Hi-Res CAM suite breaks out or
intensifies weaker scattered/ongoing convection across the eastern
Cap Rock/western Big Country into larger clusters, in a similar
regime; though with lower bases and greater moisture flux through
deeper cells, rainfall efficiency can increase from 1.25-1.5"/hr
toward isolated 2"/hr rates. 00z HREF continues to show a few
signals of such rates over 20% and localized spots of 3"+ (35-40%)
along/near the front near the Red River with an isolated 4" not
out of the realm of possibility.

This is a split signal within the guidance where a few (anchored
by the NAM/NAMnest) remain stable near the surface front allowing
greater flux toward the elevated WAA convection with higher totals
further north east into north-central OK and points north. However,
this is a minority of the suite but to account for this remaining
plausible solutions, have expanded the Marginal Risk north-
northeastward into southern KS, though rates will be lighter and
still grounds remain dry with higher FFG, no greater risk area
could be highlighted at this time, though highest probabilities
within the Marginal Risk lie with any near surface rooted cells
capable of 2"/hr.

...Northwest...
Elsewhere, the leading Atmospheric River plume approaches late in
the forecast period, likely after 24.06z. Strong onshore flow with
40-50kts of low level flow and PWat moisture values of 1-1.25" will
support IVT values over 600 kg/m/s into the Olympic Range. This
will be a good starter for the AR event, but not likely to rise any flooding/stream concerns for the Day 1 period. No Excessive
Rainfall category will be necessary for this period, but solid
rains are increasing for the Day 2 period.

Gallina


Day 2
Valid 12Z Fri Oct 24 2025 - 12Z Sat Oct 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
SOUTHERN PLAINS...

...Southern Plains...
At the start of the Day 2 period (24.12z), strong LLJ from
overnight will likely have one or more WAA convective clusters
ongoing with a higher based/elevated convection across the KS/OK
border moving toward the Ozark Plateau as left exit ascent region
of a broadening diffluent upper-level jet crosses Oklahoma prior to
the upstream mid-level cyclone exiting the Four Corners into the
southern High Plains on Friday morning. Surface cyclogenesis and
strength of moisture flux convergence within confluent return
moisture stream out of the Western Gulf across central OK will
likely help to maintain a favorable environment for further
upstream redevelopment across portions of central Oklahoma. The
mid-level low is also expected to strengthen slightly with heights
reaching 1-1.5 standard anomalies from bi- weekly means. Strong
DPVA and steepening lapse rates from advection of EML across OK
will allow for quick replenishment of unstable environment with
1000-2000 J/kg of MUCAPE along the upstream environment of the
older WAA induced convection for another bout of stronger
thunderstorms by afternoon/early evening from west-central OK south
into the Permian Basin and perhaps through the Pecos River Valley
with 1.25-1.75"/hr rates possible. Localized streak or two of 2-4"
totals with isolated total of 5"+ through late evening into early
overnight hours.

Toward midday, an upstream kicker shortwave and upper-level jet
speed max rounds the base of the closed low and ejects into the
southern High Plains providing strong mid-level ascent forcing and strengthening low level winds and therefore, moisture/instability
flux. The stream of warm, moist Western Gulf air will continue to
compile across central TX into the Red River Valley with total
Pwats starting to exceed 1.75" nearing 2". Strong directional and
speed convergence will further expand/strengthen updrafts along
the cold front/dry line, but also quickly advance eastward allowing
for strong scattered thunderstorms with 2"+/hr rates across western
into central TX. Though stronger moisture flux convergence will
allow for higher rates, the faster cell motions will likely limit
overall totals. Yet, scattered incidents of 2-4" in short-duration
is likely to result in scattered incidents of flash flooding, given
limited infiltration even in drier soil conditions/higher FFG environment.

00z guidance trends suggest a bit greater rainfall at the
beginning of the period toward northeast OK, a slightly higher
alignment of higher QPF maxima across central to northeast OK,
especially with the longer range CAM guidance. However, the general
consensus of QPF maxima also aligns nicely with the core of the
highest FFG values in the region, as well. Given the tendency of
the remaining Hi-Res CAMs to be biased toward the wetter solutions
and alignment with the FFG max, a higher confidence Slight Risk
remains in place, though if trends continue, an upgrade is not out
of the question. Further south, the run to run trends continue to
show a slow southward shift of QPF clusters supporting a small
adjustment of the Slight Risk in that direction as well.

...Pacific Northwest into Northwest California...
Only small localized adjustments were made to the old Day 3
Marginal Risk for the new Day 2 (24.12z-25.12z). The modest
Atmospheric River (AR) will push across the coastal and Cascade
ranges of WA/OR early through the period and relatively quickly the
cold front/AR plume will slide southward with respect to the
coastline into northwest CA by the end of the forecast period.
Strong broad closed low over the northeast Pacific will result in
strong height-falls nearly 2-2.5 standard anomalies from bi-weekly
mean, which is fairly impressive as it is a normal time of year for
the arrival of AR/deep lows. The low's influence provides the
strong draw of the moisture out of the central sub-tropical Pacific
with well over 1" total PWats into the coastal range and up to
.75-1" through the Columbia Valley into central WA; all while
values up to 1.5" remain offshore in the narrowing plume. Winds of
45-50kts through 850-700mb will result in peak IVT values of
700-750 kg/m/s. However, while strong, the duration is going to be
very limited given the strength of the height-falls and forward
propagation of the cold front. QPF signals remain at the 2-4"
range within the favored southwest facing orography with an
occasional rate up to .5" though fleeting; all in line with a broad
Marginal Risk of excessive rainfall.

Gallina


Day 3
Valid 12Z Sat Oct 25 2025 - 12Z Sun Oct 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
SOUTHEAST TEXAS/WESTERN LOUISIANA...

...Southern Plains into Lower western Mississippi River...
At the start of forecast period (25.12z), the combined
shortwave/closed low energy will remain progressing eastward across
the Southern Plains with strong DPVA and solid diffluence
downstream as the upstream shortwave ridge is slower to budge,
slightly amplifying across the lower Ohio and eastern Mississippi
River Valley. As such, ongoing convective activity along the cold
front will continue intersect strong moisture flux and higher
theta-E air out of the Western Gulf. Even with the approaching
upper-low, the southeastern low level ridge has remained strong
with a tight gradient supporting this strong return flow through
east Texas. The confluence of the return flow and the western Gulf
jet will remain strong across eastern TX with 35-45kts of 850mb
flow and total PWat values of 1.75 to 2".

The warm conveyor belt and thunderstorms will press eastward
through the Piney Woods while a strong TROWAL will continue to
advect above average moisture along/back west into the developing
comma head across OK into far southern KS. Instability will be
limited further north to around 250-500 J/kg suggesting some
scattered cells, but limited elevated cells will likely be limited
in overall coverage. Yet, rainfall over the two prior days may
saturate grounds and bring FFG values into a range of these cells.
As such have pulled the Marginal Risk of Excessive Rainfall across
much of eastern OK where there is supportive overlap of current day
1 & 2 forecast QPF and the TROWAL activity.

While there is likely to be a progressive squall line with intense
rainfall rates tracking through eastern TX into LA through the
morning period, generally aligned with the deeper warm conveyor
belt, lingering surface to boundary layer moisture will be
reinforced by the Western Gulf LLJ pumping higher theta-E air
northward post-WCB but ahead of the front. Solid EML will provide
lapse rates to support increasingly unstable air northward across E
TX into the afternoon/evening with CAPE values of 1500-2000 J/kg
expected, though some guidance suggests 2000-3000 J/kg across the
Coastal Plain. As such, another round of strong thunderstorms is
expected across the recovering areas from the morning line across
SE TX into W LA. As such, broad areas of 3-6" 24hr totals with
some suggestions to localized 8". There are hints of localized
training environments with the second round to support some of
these higher localized possible totals. All in all, the inherited
Slight Risk of Excessive Rainfall remains solid, though have backed
up the western edge and trimmed the southeast edge a bit,
resulting in a more SSW to NNE oblong risk area across SE TX and
much of western LA. If trends continue to tick upward, an upgrade
in category is not out of the realm of possibility going forward
into the Hi-Res CAM cycles.

...Pacific Northwest...
The core of the broad long wave/deep cyclone remains anchored
across the Gulf of Alaska though the leading height-falls/
shortwave rotated through into the Interior Northwest leaving the
lingering cold front and sub-tropical moisture plume to slowly fade
across northwest California nearing San Francisco Bay with weak
onshore winds below 30kts. Its slower progression will allow for
some localized 1-3" totals along the NW California Ranges, but
given it is over the boreal rain forest, it will likely be
beneficial. However, as large scale cyclone broadens, mid to upper-
level zonal flow will promote onshore flow of modest moisture but
also CAA aloft providing steeper lapse rates for widely scattered
showers capable of quick bursts of heavy rainfall/small hail ahead
of the next strong shortwave. This wave will bring strengthening
winds, but with the moisture axis shunted south, IVT values will
remain in the 300 kg/m/s range. This will bring another 1-3" totals
across the coastal range and some scattered 1-2" totals in the
lower foothills of the Cascades, so given this and prior activity
will hold onto the low-end Marginal Risk though have further
trimmed out shadowed areas of the Willamette Valley.

Gallina
$$
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FOUS30 KWBC 240800
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Fri Oct 24 2025

Day 1
Valid 12Z Fri Oct 24 2025 - 12Z Sat Oct 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS...

The large scale pattern still favors an active day for convection
later today through early Saturday morning over portions of the southern
Plains as strong height falls associated with an upstream
Southwest U.S. closed low/trough ejects out into the High Plains
along with a cold front. Low level moisture and stability will be
in place across much of central and northern TX as the nose of a
30 to 40+ kts southerly low-level jet rides up into the Red River
Valley region. The expectation is that organized convection should
develop initially across areas of west TX and advance east by
later in the afternoon/evening which will be capable of producing
high rainfall rates upwards of 2 inches/hour with the stronger
cells. However, the organized nature of the convection suggests
some forward propagation potential that could mitigate the overall
storm total amounts. In fact, most of the guidance supports a
fairly well- organized MCS evolution into southeast TX and near the
northwest Gulf Coast region by early Saturday morning. Maintained
the Slight Risk area with only some minor adjustments to the
western and northern periphery of the area to account for where the
axis of better instability should be along with corridors of
convective initiation. This is also in better alignment with the
consensus of the 24/00Z HREF and 23/18Z REFS guidance. Scattered
areas of flash flooding, especially for the more urbanized
locations, will be a concern.

...Pacific Northwest into Northwest California...
Only small localized adjustments were made to the Marginal Risk
area as a modest Atmospheric River (AR) pushes across the coastal
and Cascade ranges of Washington and Oregon. The plume of deepest
moisture and associated rainfall will slide southward with respect
to the coastline into northwest California by early Saturday
morning. Strong height falls and precipitable water values over 1
inch total PWats into the coastal range set up the potential for
rainfall rates of 0.75 inches to 1 inch through the Columbia Valley
into central WA with higher rainfall rates remaining off- shore.
Winds of 45-50kts through 850-700mb will result in peak IVT values
of 700-750 kg/m/s. Still agree that the duration of heaviest
rainfall is going to be very limited given the strength of the
height falls and forward propagation of the cold front. QPF signals
remain at the 2-4" range within the favored southwest facing
orography with an occasional rate up to .5" though fleeting; all in
line with a broad Marginal Risk of excessive rainfall.

Bann


Day 2
Valid 12Z Sat Oct 25 2025 - 12Z Sun Oct 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHEAST TEXAS INTO SOUTHERN ARKANSAS AND WESTERN LOUISIANA...

Multiple rounds of heavy showers and thunderstorms are expected to
impact the broader northwest Gulf Coast region this period, with
one initial axis of convection likely ongoing Saturday morning
across areas of southeast to east-central TX and advancing across
western Louisiana and southern Arkansas. This will be the
carryover of organized convection from the day 1 period which
should be interacting at least initially with a 40+ kt southerly
low-level jet off the western Gulf. Precipitable water values at or
above 1.75 inches and MUCAPE values locally of 2000+ J/kg will
support high rainfall rates potentially exceeding 2 inches/hour
with the stronger storms.

The arrival of an upper- level jet streak in the subtropical
stream combined with the interaction with the southern stream
closed low/trough axis crossing the southern Plains will favor a
renewed convective outbreak across areas of eastern Texas through
portions of western and southern Louisiana Saturday afternoon
through early Sunday. Even though antecedent conditions are quite
dry, the concern for multiple rounds of convection which combined
may yield some 3 to 5+ inch totals, will probably be enough to
support a threat for scattered areas of flash flooding. The more
sensitive urbanized locations will be at greatest risk for impacts.
For this update, the Slight Risk area was expanded given the
footprint of 2+ inch rainfall amounts within a broadened region of
instability shown by the models. This is also consistent with the
latest deterministic QPF from WPC.

...Pacific Northwest and Northwest California...

Multiple rounds of moisture transport into the coastal ranges will
continue for the period as atmospheric river activity continues.
Locally a few additional inches of rain will be possible for the
windward slopes of the terrain, but given the early-season and
relatively modest nature of this atmospheric river activity, any
flooding concerns are expected to be isolated at best. Therefore,
the Marginal Risk area is maintained with no changes for this update cycle.

Bann

Day 3
Valid 12Z Sun Oct 26 2025 - 12Z Mon Oct 27 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE MID- AND LOWER-MISSISSIPPI VALLEY AND ALONG THE PACIFIC NORTHWEST COAST...

Maintained a Marginal Risk area across portions of the southern and
middle Mississippi Valley. The risk across the southern should
diminish once a cold front passes through the area early in the
period and the deeper moisture/instability get shunted eastward.
Farther north where the moisture is not as deep...concern is more
from mid-level frontogenesis and upper level divergence leading to
locally enhanced rainfall rates where antecedent conditions have
been somewhat wetter than other locations. There is plenty
uncertainty as to whether there will be a second round of storms
capable of producing locally heavy rainfall...so overall confidence
is below average which precludes anything higher than a Marginal risk.

Bann
$$
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FOUS30 KWBC 250824
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
424 AM EDT Sat Oct 25 2025

Day 1
Valid 12Z Sat Oct 25 2025 - 12Z Sun Oct 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHEAST TEXAS INTO CENTRAL ARKANSAS AND WESTERN MISSISSIPPI...

...Previous Discussion...

Multiple rounds of heavy showers and thunderstorms are expected to
impact the broader northwest Gulf Coast region this period, with
one initial axis of on-going convection moving across parts of eastern/southeastern Texas and advancing across western Louisiana
and southern Arkansas. Convection presumably is interacting with a
40 kt southerly low-level jet off the western Gulf. Precipitable
water values at or above 1.75 inches and MUCAPE values locally of
2000 J/kg will support high rainfall rates potentially exceeding 2
inches/hour with the stronger storms.

Additional organized convection is expected later today/tonight
with the arrival of an upper- level jet streak in the subtropical
stream which interacts with the southern stream closed low/trough
axis crossing the southern Plains. Even though antecedent
conditions are quite dry, the concern for multiple rounds of
convection which combined may yield some 3 to 5+ inch totals, will
probably be enough to support a threat for scattered areas of flash
flooding. The more sensitive urbanized locations will be at
greatest risk for impacts.

...Pacific Northwest and Northwest California...

Multiple rounds of moisture transport into the coastal ranges will
continue as an atmospheric river activity continues...with greatest rates/accumulation from later this morning into the afternoon.
Locally a few additional inches of rain will be possible for the
windward slopes of the terrain, but given the early-season and
relatively modest nature of this atmospheric river activity, any
flooding concerns are expected to be isolated at best.

Bann


Day 2
Valid 12Z Sun Oct 26 2025 - 12Z Mon Oct 27 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE MID-AND LOWER-MISSISSIPPI VALLEY, TENNESSEE VALLEY, SOUTHERN
APPALACHIANS AND SOUTHEAST...

Maintained the Marginal risk area already hoisted for portions of
the southern United States on Sunday. Thunderstorms capable of
locally intense downpours remain possible across the immediate Gulf
coast early as southerly flow continues to tap Gulf moisture and
advect it northward...potentially as far north as the Tennessee
Valley. A front making its ways eastward should help focus
convective activity early in the period...but also help shunt it
eastward with time as surface high pressure builds in from the
west. Isolated cells have the potential to produce rainfall rates
in excess of an inch per hour prior to frontal passage. Farther
north...concern is more for quarter to half inch rain rates within
a weakly destabilized environment (200-400J/Kg MUCAPE). PWATs of
1-2" may support any isolated instances of excessive rainfall/flash
flooding within the marginal risk area. Models are trending toward
a higher qpf solution along the Central Gulf Coast, but their
continued to be enough uncertainty in the 24/00Z guidance to
preclude any upgrades at this time.

Bann


Day 3
Valid 12Z Mon Oct 27 2025 - 12Z Tue Oct 28 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS A PORTION
OF THE SOUTHEAST UNITED STATES...

Low pressure moving across the southern United States on day 2
will begin to take a more northeastward trajectory. Given less
favorable low level flow and a more stable atmosphere...the risk of
excessive rainfall will be diminished. Even so...the 25/00Z suite
of numerical guidance does show spotty convection with isolated
bulls-eye amounts of 2 inches or greater mainly in the Carolinas.
The NAM was far and away the most aggressive with its amounts and
was not given much consideration given the placement of the
heaviest rainfall in a region where stable air was banked up
against the east aspect of the terrain in response to the ridging
of surface high pressure to the north. While initially easy to
downplay the spotty nature of the model QPF...the machine learning
first guess algorithm did point the area as a marginal risk of
excessive roughly co-located with the WPC deterministic QPF. As a
result...we opted to shrink the Marginal issued on Day 4 and place
it closer to the southern portion of the Appalachians.

Bann
$$
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FOUS30 KWBC 260820
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
420 AM EDT Sun Oct 26 2025

Day 1
Valid 12Z Sun Oct 26 2025 - 12Z Mon Oct 27 2025

...THERE IS A SLIGHT RISK OVER PORTIONS OF THE CENTRAL GULF COAST...

Energy rotating beneath a mid-level low centered over the Middle
Mississippi Valley will help propel the convective complex through
the Southeast. Storms will move into a moisture and instability
rich environment across the immediate Mississippi/Alabama/Florida
coast during the afternoon/evening. Along the immediate coast,
precipitable water values will be between 1.5-2", which will be in
the 90th percentile of PWATs for this time of year. MUCAPE between 1000-1500J/Kg should provide enough instability to support
1-3in./hr rain rates in some places. Urban areas will be especially
susceptible to runoff from excessive rainfall. THere continues to
be a growing consensus for slower cell motions and backbuilding
storms over the immediate coast Sunday night. The Slight was
maintained for the Gulf Coast spanning from far eastern Louisiana
to the Florida Panhandle, however the northern boundary was
expanded further north into southern Mississippi and Alabama. A
broad Marginal remains in place from the central Gulf Coast to
southeast Missouri, southern Illinois and southwest Kentucky.

Campbell/Kebede


Day 2
Valid 12Z Mon Oct 27 2025 - 12Z Tue Oct 28 2025

... THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHEAST AND SOUTHERN APPALACHIANS...

Low pressure tracking through the southern tier will pivot to the
northeast allowing for convection to spread across the southern
Appalachians and Southeast. The low level flow will enter a
relatively more stable environment that will reduce the the risk
for excessive rainfall; however guidance continues to depict
isolated maximums near 2 inches across the region. A Marginal Risk
area remains in effect across eastern Tennessee, eastern Georgia,
western South Dakota and western North Carolina.

Day 3
Valid 12Z Tue Oct 28 2025 - 12Z Wed Oct 29 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Campbell
$$
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FOUS30 KWBC 270821
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
421 AM EDT Mon Oct 27 2025

Day 1
Valid 12Z Mon Oct 27 2025 - 12Z Tue Oct 28 2025

... THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHEAST/SOUTHERN Appalachians AND EASTERN FLORIDA COAST...

...SOUTHERN Appalachians/SOUTHEAST...

The latest guidance continues to focus heavy rainfall in the higher
terrain and surrounding locations in the Carolinas, northern
Georgia and eastern Tennessee. During this period, low pressure
will pivot to the northeast allowing for convection to spread
across the southern Appalachians and Southeast. 40km neighborhood
probabilities of 24hr qpf exceeding 5" is between 15-25% over
portions of far western Carolinas, while EAS neighborhood
probabilities of exceeding 3" is up to 5%. Localized amounts of
over 2" are possible especially in the terrain. Isolated maximums
near 2 inches remain possible across the region. The inherited
Marginal Risk area was maintained given the elevated threat for
local flash flooding.

...Eastern Florida...

A few locations observed several inches of rainfall that lead to
areas of flash flooding yesterday. Additional rainfall this
morning will continue to be impactful to the vulnerable coastal
locations. An approaching upper level trough is helping to aid divergence/difluence aloft. Onshore flow is allowing for sufficient
moisture and instability to move ashore, and the low- level flow
and upper level flow are nearly balanced, implying storms with
heavy rainfall shouldn't go advance too far inland. Back building
and training of convection will be possible. A Marginal Risk area
was hoisted for the eastern coastline given the potential impacts
from additional rainfall over saturated soils.

Campbell


Day 2
Valid 12Z Tue Oct 28 2025 - 12Z Wed Oct 29 2025

...MID-MISSISSIPPI VALLEY/TENNESSEE VALLEY...

A cold front effecting from the West into the Plains will have
scattered to widespread showers and thunderstorms associated with
it during this period. While rain falling over parts of the central
U.S. will be beneficial given decent drought conditions, there is
a growing signal that heavy rain may focus over the Mid/Lower
Mississippi Valley thus increases the risk the potential for
isolated areas of flash flooding. A Marginal Risk was introduced
covering southeast Missouri, eastern Arkansas, northern
Mississippi, northwest Alabama, western Tennessee, and western Kentucky.

Campbell


Day 3
Valid 12Z Wed Oct 29 2025 - 12Z Thu Oct 30 2025

...SOUTHERN AND CENTRAL Appalachians/SOUTHEAST/MID-ATLANTIC...

The closed low will pivot from the Mid-South to the Southeast/Mid-
Atlantic allowing for showers and thunderstorms to overspread the
Tennessee Valley/Carolinas/Mid-Atlantic region. Recent rainfall
over this region will have lowered local FFG and elevated risk for
heavy rainfall and local flash flooding concerns. A Marginal Risk
area spans from northern Georgia northward to West Virginia and
from central Kentucky to the western Carolinas and Virginia.

Campbell
$$
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FOUS30 KWBC 280759
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
359 AM EDT Tue Oct 28 2025

Day 1
Valid 12Z Tue Oct 28 2025 - 12Z Wed Oct 29 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Campbell


Day 2
Valid 12Z Wed Oct 29 2025 - 12Z Thu Oct 30 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS THE
SOUTHERN AND CENTRAL APPALACHIANS AND SURROUNDING PORTIONS OF THE OHIO/TENNESSEE VALLEYS...

Rainfall is expected to overspread the Tennessee/Ohio Valley with
anomalous low- level moisture transport driving east-southeast
moisture transport into the Southern/Central Appalachians as a
closed upper low swivels from the Mid-South to the Ohio Valley.
Much of this part of the country will experience beneficial
moisture; however there will be embedded locations that have the
potential for hourly rates of 1-1.5 inches/hour that could result
in localized flash flooding. This is despite limited instability
(similar to Day 2 across the Mid- South), as the dynamics of the
closed low (notable PV anomaly with enhanced divergence aloft via
left exit region of ~130 kt jet streak @ 250 mb) may result in
localized 2" exceedance in the Ohio/Tennessee Valley (with terrain
forcing primarily driving any localized 2" exceedance along/east
of the Southern/Central Appalachians).

Campbell/Churchill


Day 3
Valid 12Z Thu Oct 30 2025 - 12Z Fri Oct 31 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS THE
SOUTHERN PORTION OF THE NORTHEAST...

The system mentioned for the day 2 period will continue to advance
up the Eastern Seaboard directing widespread rain to the Northeast.
Guidance is suggesting the highest rainfall accumulations will
focus over northern New Jersey and southeast New York where WPC
has areal averages of 1.5-2.5 inches forecast for this period. This
part of the region is where the best potential for reaching or
exceeding local FFG guidance so a Marginal Risk area remains in
effect for portions of New Jersey, Pennsylvania, New York, and
Connecticut.


Campbell
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FOUS30 KWBC 290739
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
339 AM EDT Wed Oct 29 2025

Day 1
Valid 12Z Wed Oct 29 2025 - 12Z Thu Oct 30 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS THE
SOUTHERN AND CENTRAL APPALACHIANS AND SURROUNDING PORTIONS OF THE OHIO/TENNESSEE VALLEYS...

Rainfall is expected to overspread the Tennessee/Ohio Valley with
anomalous low- level moisture transport driving east-southeast
moisture transport into the Southern/Central Appalachians as a
closed upper low swivels from the Mid-South to the Ohio Valley. HREF neighborhood probs for >2" are relatively high in-of the Blue
Ridge from Virginia down into the western Carolinas (60-90%) with a
vast majority of the rain coming from shallow convective processes
focused within the terrain. Large scale forcing across the
aforementioned areas will be the primary driver for the heavy rain
scenario, however a tongue of elevated theta_E is expected to
advect off the Atlantic into the Central Apps/Blue Ridge leading to
a greater potential for that low- topped convection to impact
these zones. A Marginal Risk area remains in effect for this part
of the nation.

Campbell/Kleebauer


Day 2
Valid 12Z Thu Oct 30 2025 - 12Z Fri Oct 31 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS THE
SOUTHERN PORTION OF THE NORTHEAST...

This system is forecast to track to the northeast as the
associated surface low strengthens over the Mid-Atlantic onward to
the Northeast. Heavy rain will accompany the low and overspread the
region. The best threat for convective enhancement leading to
better rates >1"/hr and some minor training off steady southeast
flow off the Atlantic will occur from southeast Pennsylvania up
through New Jersey, New York City metro, and western Long Island
to about the I-95 corridor in Connecticut. A Marginal Risk for
excessive rainfall and isolated flash flood concerns in that
urbanized corridor of the Northeastern U.S. remains for this period.

Campbell/Kleebauer


Day 3
Valid 12Z Fri Oct 31 2025 - 12Z Sat Nov 01 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR WESTERN
WASHINGTON...

Heavy precipitation is likely Friday into Saturday for portions of
the Pacific Northwest as a moderately strong atmospheric river
streams onshore ahead of a larger northeast Pacific low. Areal
averages of 1 to 3 inches will be common with the potential for
local maximums of 4+ inches. A Marginal Risk for excessive rainfall
and isolated flash flooding concerns is in effect for western
Washington. Most precipitation is forecast to stay rain other
than snow even in the highest peaks of the Olympics through Friday,
with more snow in the Cascades.

Campbell
$$
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FOUS30 KWBC 300720
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
320 AM EDT Thu Oct 30 2025

Day 1
Valid 12Z Thu Oct 30 2025 - 12Z Fri Oct 31 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE MID ATLANTIC AND NORTHEAST...

An occluded cyclone is forecast to track to the northeast as its
surface low strengthens over the Mid-Atlantic and moves northeast,
drawing in increasingly higher moisture from Hurricane Melissa.
Strong 850 hPa inflow near 50 kts and sufficient instability (500+
J/kg of MU CAPE) is forecast to overspread the region. Hourly
amounts rising into the 1-2" range could occur from southeast
Pennsylvania up through New Jersey, Long Island, and portions of
southwest New England, with local totals to 4" possible within 2-3
hours. Despite recent drought, this could be problematic in urban
areas and where recent leaf fall has clogged drainage.

A Marginal Risk for excessive rainfall and isolated flash flood
concerns remains for this period; the system's progression should
hold off any broad areas with a higher risk of flash flooding. It
should be noted, however, that a spot or two within southern
Upstate NY and northeast PA have a ~20% chance of 5"+ per the HREF
and REFS guidance, so localized Slight Risk impacts cannot be
ruled out.

Roth


Day 2
Valid 12Z Fri Oct 31 2025 - 12Z Sat Nov 01 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR NORTHWESTERN
WASHINGTON STATE...

A modestly strong atmospheric river will setup across the Pacific
Northwest Northwest with an advection of high IVT (>750 Kg/ms)
into the region beginning Friday afternoon, carrying through the
late evening Friday into Saturday. Inflow at 850 hPa approaches 50
kts out of the southwest while precipitable water values in the
coastal ranges rise into the 1.25-1.5" range. MU CAPE is forecast
to remain weak, under 250 J/kg. Precip rates should rise to
between 0.5-0.75"/hr during the peak of the heavy rainfall,
producing local amounts of 3-5" in the higher terrain of western
WA, which would be particularly challenging for the Skokomish
river. Considering the consistency within guidance on totals and
expectation for some enhanced rates to generate river rises and
minor flooding, a Marginal Risk was maintained, with some expansion
to the south to account for the wetter 00z UKMET solution.

Roth


Day 3
Valid 12Z Sat Nov 01 2025 - 12Z Sun Nov 02 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Roth
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FOUS30 KWBC 310713
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
313 AM EDT Fri Oct 31 2025

Day 1
Valid 12Z Fri Oct 31 2025 - 12Z Sat Nov 01 2025

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR WESTERN
WASHINGTON AND FAR NORTHWESTERN OREGON...

A modestly strong atmospheric river will setup across the Pacific
Northwest with an advection of high IVT (>750 Kg/ms) into the
region from afternoon through late evening. Inflow at 850 hPa
approaches 50 kts out of the southwest while precipitable water
values in the coastal ranges rise into the 1.25-1.5" range, though
little to no instability is forecast. Precip rates will generally
remain below 0.5"/hr, but may locally peak between 0.5-0.75"/hr.
This may result in localized amounts of 2-5" in the higher terrain
of western WA and far northwestern OR, which would be particularly
challenging for the Skokomish river. Given the consistency of the
forecast and the expectation for some enhanced rates to generate
river rises and minor flooding, a Marginal Risk was maintained and
expanded a bit south into far northwestern OR.

Churchill/Roth


Day 2
Valid 12Z Sat Nov 01 2025 - 12Z Sun Nov 02 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Churchill


Day 3
Valid 12Z Sun Nov 02 2025 - 12Z Mon Nov 03 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Churchill
$$
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FOUS30 KWBC 021518
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1018 AM EST Sun Nov 2 2025

Day 1
Valid 12Z Sun Nov 02 2025 - 12Z Mon Nov 03 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Several model solutions are fairly aggressive in depicting heavy
rainfall along coastal areas of North Carolina tonight into early
tomorrow (Monday). Cooling aloft (from eastward movement of a deep
mid/upper trough currently over Middle Tennessee) and
warming/moistening (from advection over the Gulf Stream) may
result in enough surface-based instability for deep convection
along coastal areas and the Outer Banks. Concerns about the
magnitude of instability and sensitivity of ground conditions (with
marshy ground areas and only modest streamflow signals via USGS
Water Dashboard) lend considerable doubt regarding inland flash
flood potential. A small Marginal area might be needed in later
and/or special outlook updates if inland convective signals become
more pronounced later this evening.

Cook/Churchill


Day 2
Valid 12Z Mon Nov 03 2025 - 12Z Tue Nov 04 2025

The probability of rainfall exceeding flash flood guidance is less
than 5 percent.

Churchill


Day 3
Valid 12Z Tue Nov 04 2025 - 12Z Wed Nov 05 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTHWESTERN CALIFORNIA AND FAR SOUTHWESTERN OREGON...

The next strong landfalling atmospheric river (IVT > 750 kg/ms)
looks to impact coastal portions of northern CA/far southwestern OR
come Tuesday afternoon, likely peaking in strength in the evening
to overnight period. Initial low-level flow earlier in the day
looks more ideally directed perpendicular to the coast/mountains,
but by the time higher IVT sets in veering to the SW-SSW may
mitigate the effectiveness of the topographic lift (with otherwise
limited instability as MUCAPE of less than 250 J/kg is forecast).
Even still, this is a relatively warm system (with the cold core
staying offshore until beyond Day 3) and PWATs of 1.2-1.4" are in
the vicinity of the 90th percentile climatologically. Rainfall
totals of 2-4" are generally expected (and may locally exceed 4"),
and much of that could occur in a 6-12 hour period. The inherited
Marginal Risk is sufficient (in-line with the latest GEFS-driven
machine learning first guess field) and has been maintained (with
only minor adjustments based on the latest models QPF footprint).
Any flash flood impacts are most likely where relatively high
rainfall rates (0.25"+/hr) coincide with sensitive burn scars.

Churchill
$$
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