FOUS30 KWBC 020806
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
406 AM EDT Thu Apr 2 2026

Day 1
Valid 12Z Thu Apr 02 2026 - 12Z Fri Apr 03 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTHERN ILLINOIS, WISCONSIN AND MICHIGAN...

The primary area of interest for flash flooding will likely lie
over far northern Chicago suburbs up into the Milwaukee metro due
to the areal urban footprint and suggestion of heavier rainfall in
the area, especially the second round of convection. Fortunately,
rates are generally capped at 1-1.25"/hr at peak intensity with
much of the CAMs hourly outputs closer to 0.5-1"/hr for the
heaviest periods of impact. This lies right on the edge of any FFG
exceedance, so the threat will be somewhat capped overall for a
multitude of reasons. There will likely be two main rounds- the
first in the morning hours followed by a most robust line during
the afternoon when there will be more ample large scale
forcing/instability as the surface cold front approaches from the
West. Overall areal averages across the region will be in the 1-2
inch range with locally isolated higher amounts possible.

Campbell/Kleebauer


Day 2
Valid 12Z Fri Apr 03 2026 - 12Z Sat Apr 04 2026

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

Strong to severe thunderstorms along with embedded heavy rainfall
will track across the Southern/Central Plains into the Mississippi Valley/Midwest during this period. Moisture (with PWs over the
90th, perhaps 95th percentile) and instability are likely to pool
along and ahead of the associated cold front and produce widespread
convection. Storms likely beginning in the afternoon are expected
to get reinforced through the evening and night hours as a low
level jet picks up ahead of the cold front. Given that some of this
region has been drier, it will take awhile before there are
substantial flash flood concerns. Some of the highest amounts/rates
are likely to focus over parts of central and eastern Oklahoma
down into the Red River Basin between the Texas and Oklahoma
border. Consensus has areal averages of 1 to 3 inches while some of
the hi-res guidance is hinting at isolated maximums of 4 to 7
inches. Slight Risk area spans from north-central Texas to
southwest-southern Missouri.

Campbell/Kleebauer


Day 3
Valid 12Z Sat Apr 04 2026 - 12Z Sun Apr 05 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE CENTRAL
AND EASTERN GREAT LAKES SOUTHWESTWARD TO CENTRAL TEXAS AND THE
LOWER MISSISSIPPI RIVER VALLEY...

Much of the convection that evolves across the Marginal Risk area
on D3/Sat will depend on specific evolution of convective complexes
that originate from the central/southern Plains on D2/Fri. Although
those details are a bit uncertain at the time frame, general
consensus is that one or two MCSs will traverse the Mississippi Valley/Mid-South early in the forecast period before convective
redevelopment occurs upstream along a composite outflow/cold front
during peak heating hours from central Texas to Mississippi. Areas
of training are likely if this pattern holds, with initiating
boundaries supporting deep convection eventually becoming more
parallel to steering flow aloft. Portions of this region may
require an upgrade to Slight in later outlook updates.

Farther north, convective coverage is far less certain -
particularly from Illinois to Ohio. Deeper convection south of
these areas could disrupt inflow/instability and lead to a minimum
in precipitation in these areas. Again - this regime is uncertain.

The primary reason Marginal was maintained for D3 from Illinois
eastward to New York State and West Virginia was soils/local
sensitivity. Soils are wetter with eastern extent from prior
rainfall and could still be sensitive to even moderate rainfall by
D3/Sat in a few spots.

Cook
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 030803
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
403 AM EDT Fri Apr 3 2026

Day 1
Valid 12Z Fri Apr 03 2026 - 12Z Sat Apr 04 2026

...THERE IS SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS INTO THE OZARKS, MISSOURI VALLEY, AND UPPER
MISSISSIPPI VALLEY...

At the mid-levels, a stout wave over the Intermountain West
(centered over Wyoming) will migrate eastward throughout the day,
spreading increasingly strong mid-level flow and height falls from
the High Plains eastward toward the Mid/Upper Mississippi Valley.
At the surface, strong 850mb flow and poleward flux of
moisture/instability will become established along and ahead of a
low initially across the Kansas/Nebraska border region at the
beginning of the forecast period and persist through 12Z Sat. Late
in the forecast period, a cold front will migrate southward across
the southern Plains. Areas of scattered thunderstorms are expected
along and ahead the front and low especially during the afternoon
and evening, with several areas of flash flooding expected.

The primary area for flash flood potential will exist along the
OK/TX Red River vicinity southward toward central Texas and the Big
Country. Scattered thunderstorms are expected to develop during
the afternoon and evening across the region, with CAMs suggestive
of training/repeating behavior and local areas of 2-5 inch totals.
The glancing influence of the aforementioned mid-level wave across
the region lends some doubt on degree and location of
daytime/afternoon convective coverage, which should modulate the
flash flood risk substantially.

Even if convection materializes as depicted by CAMs, antecedent
dryness of ground conditions are a mitigating factor for a more
widespread or significant flash flood risk. Persistent training
will likely be needed for ground conditions to lose receptiveness
to rainfall on a widespread basis. Both pre-frontal convection and
convection moving in along a surface cold front late represent two
distinct regimes for heavy rain and flash flood potential - with
that risk eventually spreading toward I-35 in Texas and the DFW
Metroplex area through early Saturday.

Farther north, convection along the front will likely sweep through
portions of Missouri and Oklahoma, with a greater risk/potential
for multiple mergers and/or convective clusters with southward
extent. Areas just southeast of Kansas City received copious
amounts of rain Thursday and will probably not have fully recovered
before the incoming thunderstorm threat through early Saturday,
necessitating maintenance of Slight Risk probabilities there.

Lastly, models (primarily CAMs) depict potential for
repeating/training convection across portions of northeastern Iowa
and vicinity through much of the day (from 16-18Z through well into
the evening) along/near a surface warm front and well ahead of an eastward-moving cold front that should reach the area late in the
forecast period. NASA Sport soil moistures suggests slightly more
moist ground conditions in these areas, and the advance of the
mid-level wave and confluence on the northern end of strong 850mb
flow all point to prolonged deep convective potential. 3-5 inch
totals cannot be ruled out in this regime. A Slight Risk has been
added to the outlook in these areas as a result.

Though less widespread, additional convection should traverse wet
ground conditions across portions of Ohio, Pennsylvania, and
southern New York State, supporting continued Marginal
probabilities in that area.

Cook


Day 2
Valid 12Z Sat Apr 04 2026 - 12Z Sun Apr 05 2026

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FROM THE CENTRAL
AND EASTERN GREAT LAKES SOUTHWESTWARD TO CENTRAL TEXAS AND THE
LOWER MISSISSIPPI RIVER VALLEY...

Much of convective evolution during the D2/Sat forecast period will
depend on convective details from lingering convection across
Arkansas and Texas left over from D1/Fri. East-northeastward
progression of a mid-level wave toward the Great Lakes will aid in southeastward movement of a cold front from the Plains through the Ozarks/Mid-Mississippi Valley during the forecast period. This
front will gradually become more parallel to weakening flow aloft
from Texas to Mississippi, supporting additional opportunities for
training convection as storms organize along remnant outflows and
backbuild. This regime suggests that pockets of 1-3 inch rainfall
totals are likely especially from central Texas to northern
Alabama, with heavier totals also possible from central Mississippi
south into southeastern Louisiana as well. While Slight Risk
potential exists with this setup, concerns about 1) uncertainty of
prior-day convective evolution and 2) antecedent dryness continue
to be limiting factors for a more widespread flash flood risk at this time.

Farther north, convection is likely to be progressive across much
of the Lower Ohio Valley along with potential for inhibited
destabilization due to more widespread convection across the Lower
Mississippi Valley. Too much uncertainty exists to reduce the
Marginal Risk area at this time. Notable exceptions to this general
regime exist, however, from northern Ohio into southern New York
State and Pennsylvania, where models suggest appreciable daytime
heating and moderate instability developing. Storms may not be all
that fast moving either in Pennsylvania as that region should
reside on the southern extent of stronger mid-level flow into
southeastern Canada. Convective coverage is a bit uncertain, but
any greater-than-anticipated coverage of convection in this
environment could locally raise flash flood concerns - especially
with low FFGs noted across that area.

Cook


Day 3
Valid 12Z Sun Apr 05 2026 - 12Z Mon Apr 06 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
SOUTH TEXAS ON SUNDAY...

Maintained the Marginal Risk of Excessive rainfall area that was
introduced by the WPC Medium Range desk as a west-to-east oriented
front makes its way southward. Deeper moisture should e pooling
along and south of the boundary with precipitable water values
around 1.75 inches in place at the start of the outlook period.

Given uncertainties detailed n the Day 2 period with respect to the
timing and placement...combined with the 03/00Z NCEP global models
now showing the front to be more progressive than in earlier runs
which led to CAPE being swept out of South Texas faster...was not
inclined to introduce a Slight Risk area at this point. At the same point...spaghetti plots from the non-CAM ensembles still show
enough members with 1 inch QPF and a few contours of 2 inch QPF to
support keeping the Marginal area with only minor nudges around the periphery.

Bann
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 030803
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
403 AM EDT Fri Apr 3 2026

Day 1
Valid 12Z Fri Apr 03 2026 - 12Z Sat Apr 04 2026

...THERE IS SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS INTO THE OZARKS, MISSOURI VALLEY, AND UPPER
MISSISSIPPI VALLEY...

At the mid-levels, a stout wave over the Intermountain West
(centered over Wyoming) will migrate eastward throughout the day,
spreading increasingly strong mid-level flow and height falls from
the High Plains eastward toward the Mid/Upper Mississippi Valley.
At the surface, strong 850mb flow and poleward flux of
moisture/instability will become established along and ahead of a
low initially across the Kansas/Nebraska border region at the
beginning of the forecast period and persist through 12Z Sat. Late
in the forecast period, a cold front will migrate southward across
the southern Plains. Areas of scattered thunderstorms are expected
along and ahead the front and low especially during the afternoon
and evening, with several areas of flash flooding expected.

The primary area for flash flood potential will exist along the
OK/TX Red River vicinity southward toward central Texas and the Big
Country. Scattered thunderstorms are expected to develop during
the afternoon and evening across the region, with CAMs suggestive
of training/repeating behavior and local areas of 2-5 inch totals.
The glancing influence of the aforementioned mid-level wave across
the region lends some doubt on degree and location of
daytime/afternoon convective coverage, which should modulate the
flash flood risk substantially.

Even if convection materializes as depicted by CAMs, antecedent
dryness of ground conditions are a mitigating factor for a more
widespread or significant flash flood risk. Persistent training
will likely be needed for ground conditions to lose receptiveness
to rainfall on a widespread basis. Both pre-frontal convection and
convection moving in along a surface cold front late represent two
distinct regimes for heavy rain and flash flood potential - with
that risk eventually spreading toward I-35 in Texas and the DFW
Metroplex area through early Saturday.

Farther north, convection along the front will likely sweep through
portions of Missouri and Oklahoma, with a greater risk/potential
for multiple mergers and/or convective clusters with southward
extent. Areas just southeast of Kansas City received copious
amounts of rain Thursday and will probably not have fully recovered
before the incoming thunderstorm threat through early Saturday,
necessitating maintenance of Slight Risk probabilities there.

Lastly, models (primarily CAMs) depict potential for
repeating/training convection across portions of northeastern Iowa
and vicinity through much of the day (from 16-18Z through well into
the evening) along/near a surface warm front and well ahead of an eastward-moving cold front that should reach the area late in the
forecast period. NASA Sport soil moistures suggests slightly more
moist ground conditions in these areas, and the advance of the
mid-level wave and confluence on the northern end of strong 850mb
flow all point to prolonged deep convective potential. 3-5 inch
totals cannot be ruled out in this regime. A Slight Risk has been
added to the outlook in these areas as a result.

Though less widespread, additional convection should traverse wet
ground conditions across portions of Ohio, Pennsylvania, and
southern New York State, supporting continued Marginal
probabilities in that area.

Cook


Day 2
Valid 12Z Sat Apr 04 2026 - 12Z Sun Apr 05 2026

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FROM THE CENTRAL
AND EASTERN GREAT LAKES SOUTHWESTWARD TO CENTRAL TEXAS AND THE
LOWER MISSISSIPPI RIVER VALLEY...

Much of convective evolution during the D2/Sat forecast period will
depend on convective details from lingering convection across
Arkansas and Texas left over from D1/Fri. East-northeastward
progression of a mid-level wave toward the Great Lakes will aid in southeastward movement of a cold front from the Plains through the Ozarks/Mid-Mississippi Valley during the forecast period. This
front will gradually become more parallel to weakening flow aloft
from Texas to Mississippi, supporting additional opportunities for
training convection as storms organize along remnant outflows and
backbuild. This regime suggests that pockets of 1-3 inch rainfall
totals are likely especially from central Texas to northern
Alabama, with heavier totals also possible from central Mississippi
south into southeastern Louisiana as well. While Slight Risk
potential exists with this setup, concerns about 1) uncertainty of
prior-day convective evolution and 2) antecedent dryness continue
to be limiting factors for a more widespread flash flood risk at this time.

Farther north, convection is likely to be progressive across much
of the Lower Ohio Valley along with potential for inhibited
destabilization due to more widespread convection across the Lower
Mississippi Valley. Too much uncertainty exists to reduce the
Marginal Risk area at this time. Notable exceptions to this general
regime exist, however, from northern Ohio into southern New York
State and Pennsylvania, where models suggest appreciable daytime
heating and moderate instability developing. Storms may not be all
that fast moving either in Pennsylvania as that region should
reside on the southern extent of stronger mid-level flow into
southeastern Canada. Convective coverage is a bit uncertain, but
any greater-than-anticipated coverage of convection in this
environment could locally raise flash flood concerns - especially
with low FFGs noted across that area.

Cook


Day 3
Valid 12Z Sun Apr 05 2026 - 12Z Mon Apr 06 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
SOUTH TEXAS ON SUNDAY...

Maintained the Marginal Risk of Excessive rainfall area that was
introduced by the WPC Medium Range desk as a west-to-east oriented
front makes its way southward. Deeper moisture should e pooling
along and south of the boundary with precipitable water values
around 1.75 inches in place at the start of the outlook period.

Given uncertainties detailed n the Day 2 period with respect to the
timing and placement...combined with the 03/00Z NCEP global models
now showing the front to be more progressive than in earlier runs
which led to CAPE being swept out of South Texas faster...was not
inclined to introduce a Slight Risk area at this point. At the same point...spaghetti plots from the non-CAM ensembles still show
enough members with 1 inch QPF and a few contours of 2 inch QPF to
support keeping the Marginal area with only minor nudges around the periphery.

Bann
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 060817
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
417 AM EDT Mon Apr 6 2026

Day 1
Valid 12Z Mon Apr 06 2026 - 12Z Tue Apr 07 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF FLORIDA...

Maintained the Marginal Risk area introduced on Sunday across
portions of Florida as a trailing tail of a cold front advancing
offshore the East Coast will be slowly moving through central
portions of the state. The front will provide a focus for showers
and thunderstorms to fire up along within the moist tropical
airmass. The 00Z HREF and RRFS neighborhood probabilities showed
several hours during which the rainfall rates pulsate between
0.50"/hr to 3+"/hr mainly from this afternoon into the evening.
Consequently there were not changes made.

Bann


Day 2
Valid 12Z Tue Apr 07 2026 - 12Z Wed Apr 08 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE EAST COAST OF THE FLORIDA PENINSULA...

A cold front will be passing over Florida which allows for deep
moisture to pool across the southern two-thirds of the peninsula with precipitable water values reaching into the 1.5 to 1.8 inch range
and moisture flux convergence along the front acts to focus and
support convection. The concern about excessive rainfall arises
from the locally heavy rainfall rates from any convection that
develops within such an environment as well as the fact that the
front should be slowing its southward motion keeps the window of
opportunity open longer for enhanced rainfall totals.

Bann


Day 3
Valid 12Z Wed Apr 08 2026 - 12Z Thu Apr 09 2026

...THERE CONTINUES TO BE A MARGINAL RISK OF EXCESSIVE RAINFALL OVER
PARTS OF THE FLORIDA PENINSULA...

A front draped across the southern portion of the Florida
peninsula acting as a focus for thunderstorms capable of producing
locally heavy rainfall across parts of the Florida peninsula. Some
of the guidance has a mesoscale low over the eastern Gulf that
begins to move towards the peninsula and starts to lift the front
northward during the latter part of the period. The inference is
that low level flow will be strengthening...especially on the
eastern side of the peninsula...which may enhance rainfall
amounts compared with amounts on Tuesday. Given the lack of
agreement within the suite of numerical guidance on where...or
if...this occurs preludes more than a Marginal risk area.

Bann
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 070828
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
428 AM EDT Tue Apr 7 2026

Day 1
Valid 12Z Tue Apr 07 2026 - 12Z Wed Apr 08 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE ATLANTIC SIDE OF THE FLORIDA PENINSULA TODAY...

Introduced a Slight Risk area across the Atlantic side of the
peninsula in an environment conducive of focusing and sustaining
locally heavy rainfall amounts and rainfall rates into the evening
hours. There had been showers and some thunderstorms on Monday
afternoon and evening...but the approach of a mid and upper level
feature helped increase coverage of light to moderate rainfall in
the overnight hours prior to the start of the Day 1 period at
07/12Z. Thinking is that this will help prime the soils enough to
slow the intake a bit of additional rain later today.

Additional showers and thunderstorms should develop during the day
along a slow moving cold front making its way southward in an
atmosphere with precipitable water approaching 1.75 inches. That
should support some downpours anywhere along the central or
southern peninsula on the Atlantic side. Additionally...there looks
to be a period of renewed moisture infusion by strengthening
easterly winds off the Atlantic following frontal passage which
enhances the potential for flooding.

The 00Z runs of the HREF and RRFS both maintain 10 to 20 percent
neighborhood probabilities of 3 inches of rain in 3 hours (broadly
speaking) from Cape Canaveral to Miami until 08/00Z and roughly the
same range for 24 hour amounts exceeding 5 inches. Despite the
disagreement shown by HREF and RRFS exactly as to where the highest probabilities occur...the presence of ingredients along a corridor
that has stretches of surfaces impervious to water because of
urbanization supported an upgrade.

Bann


Day 2
Valid 12Z Wed Apr 08 2026 - 12Z Thu Apr 09 2026

...THERE IS A Marginal RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE EASTERN FLORIDA PENINSULA ON WEDNESDAY...

The 07/00Z suite of numerical guidance lingered additional rainfall
into the Day 2 as a quasi stationary front remains present. Even
so...the guidance maintained focus mainly along the eastern
coastline as having an elevated threat for urban flash flooding
concerns. There were a few nudges based on the latest guidance but
the overall changes did not reflect a fundamental change in
forecast reasoning. The QPF did not normally suggest a Slight
risk...but the need for one will be revisited based on how much
rain falls and where it falls today and tonight.

Bann


Day 3
Valid 12Z Thu Apr 09 2026 - 12Z Fri Apr 10 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PARTS OF THE NORTHERN/CENTRAL PLAINS...

There is a growing consensus among the models for heavy to
excessive rainfall threat shaping up on Thursday given
strengthening return flow from the Gulf region encounters the
leading edge of colder air coming out of Canada and the northern
US. Precipitable water values between 0.8 and 1.0 inches and CAPE
values in excess of 1500 J per kg will encounter the
front...resulting in storms that could result in heavy to
potentially excessive rainfall Thursday into Thursday night/early Friday.

Bann

$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 080825
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
425 AM EDT Wed Apr 8 2026

Day 1
Valid 12Z Wed Apr 08 2026 - 12Z Thu Apr 09 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE EASTERN FLORIDA PENINSULA...

A persistent pattern of northeasterly flow into the eastern FL
Peninsula along with a quasi-stationary front bisecting portions of
the state will lead to another round of scattered convective
activity starting later today which may produce localized flash
flooding. The best chance for this to occur will be across the
urban settings along the I-95 corridor stretching from Daytona
Beach down to the Miami metro with the latest HREF blended mean QPF
generally heaviest near the Treasure Coast where convergence along
the stationary front. This should serve as an anchor point for
storms. Other prospects for heavy rain will likely be along the
immediate coast due to frictional convergence spurred by the
prevailing northeasterly surface flow coupled with a moderate
effective shear layer between 30-40kts in an environment
characterized by CAPE values in the 1000 to 2000 J/kg range.

Areal neighborhood probabilities from the HREF and RRFS for >3"
remains very similar to values on Monday along a majority of the
eastern peninsula coast line. Suspect the RRFS was a bit too
excitable with its areal extent and neighborhood probabilities
although not entirely not of the realm of possibilities.
Precipitable water values will remain 1 to 2 standard deviations
above normal over the southern half of FL which would be sufficient
for those heavier cores to materialize when convection occurs.

Considering some overlap over the past few days, maintained the
Slight risk area introduced on Monday.

Bann


Day 2
Valid 12Z Thu Apr 09 2026 - 12Z Fri Apr 10 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PARTS OF THE
CENTRAL PLAINS AND SOUTHERN FLORIDA PENINSULA...

...Plains...
The general synoptic pattern across the Central CONUS
remains consistent on a run-to-run basis. That means there is the
potential for locally heavy rainfall that produces isolate flash
flooding from Kansas to points northeastward into northern Illinois
from late Thursday into Thursday night and early Friday morning.

A weak shortwave ejecting out of the Central Rockies will
intersect a slow-moving cold front propagating out of the Upper
Midwest and Northern Plains creating a focused axis of ascent along
and just ahead of the front as it migrates through the Plains and
Central Midwest. Areal QPF average of 1-3 inches remains in the
forecast within vicinity of the front with much of the rain
occurring in a window between 10/00Z and 10/12z Friday as return
flow from the Gulf approaches the front. The magnitude of rainfall
and antecedent soil moisture anomalies pin this into the
traditional MRGL risk threshold.

...Florida...
A threat for showers and a few thunderstorms will linger across
portions of the southern Florida peninsula on Thursday before the
system moves away from the area completely. The 08/00Z NCEP
guidance still generated isolated maximum areal-average QPF in
excess of an inch over the highly urbanized corridor. Felt it was
too early to remove the excessive rainfall area at this point.

Bann


Day 3
Valid 12Z Fri Apr 10 2026 - 12Z Sat Apr 11 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL PLAINS...

The southward moving cold front which is expected to serve as a
focus for some heavy rainfall on Thursday will continue to move
southward and once again be the focus for convection that may
produce excessive rainfall on Friday over portions of the Central
or Southern Plains. The airmass will be moderately unstable with
MUCAPE values peaking in the 1000 to 1500 J/kg range in area where
precipitable water values peak close to 1.5 inches on Friday
afternoon...which should foster decent rainfall rates and the
potential for excessive rainfall amounts.

Bann
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 090823
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
423 AM EDT Thu Apr 9 2026

Day 1
Valid 12Z Thu Apr 09 2026 - 12Z Fri Apr 10 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PARTS OF THE
CENTRAL PLAINS, LOWER MISSOURI AND MID-MISSISSIPPI VALLEYS AND
ALONG THE EAST COAST OF FLORIDA...

...Central Plains to Mid-Mississippi Valley...
The surface frontal boundary stretching from the Central Plains
into the Mid Mississippi Valley is expected to be nearly stationary
day 1, remaining oriented in a general west to east direction.
In the wake of the strong height falls moving northeast from the
Upper Lakes into southeast Canada, additional shortwave energy
expected to dive southeast from the Northern Plains into the Upper
MS Valley. These height falls will help strengthen the low level
south southwesterly flow into this boundary, push PW values to 1
to 2+ standard deviations above the mean and enhance uvvs in the
above average PW axis in the vicinity of the stationary front. This
will support increasing convection late Thursday afternoon into
the early hours of Friday in the vicinity of this boundary with
locally heavy rainfall totals and isolated runoff issues. Only
some minor changes made to the previous marginal risk area,
trimming it to the northwest across northern IL, and extending it
slightly farther south into northeast KS to match the latest model
qpf consensus. The marginal risk fits well with where the latest
HREF neighborhood probabilities are highest for 1 and 2"+ totals
during the upcoming day 1 period.

...East coast of Florida...
The strong low level east northeasterly flow will continue for at
least the beginning of the day 1 period along the east coast of
Florida. PW values will remain above average during the day on
Thursday, before beginning to decrease as the low level onshore
flow weakens after 0000 UTC Friday. There will continue to be the
threat of locally heavy rains from slow moving to nearly stationary
rain bands in this strong moist onshore flow region. Confidence is
not great with placement, leading to little in the way of changes
with to the previous broad marginal risk area along the east
central to southeast Florida coastal region, with the greatest risk
of runoff issues in more urbanized regions.

Oravec


Day 2
Valid 12Z Fri Apr 10 2026 - 12Z Sat Apr 11 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL TO SOUTHERN PLAINS...

The west to east front stretching from the Central Plains into the Mid-Mississippi Valley day 1 will begin to push southward late day
1 into early day 2. This front will then again becoming stationary
during the day on Friday, oriented west to east from the Central
Plains, east into the Lower MO Valley and Mid-Mississippi Valley.
Similar to the day 1 period, PW values should increase in the
vicinity of this front in response to strengthening southerly low
level inflow. Shortwave energy pushing northeastward into this high
PW axis in the vicinity of this front will support areas of slow
moving convection along this front, locally heavy rains and
isolated runoff issues. The previous marginal risk area was pushed
southward by approximately 50-75 miles to fit the latest model qpf
consensus. There still is some latitudinal spread with the max qpf
axis, with the more southern solution favored in the latest WPC qpf.

Oravec


Day 3
Valid 12Z Sat Apr 11 2026 - 12Z Sun Apr 12 2026

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

An axis of much above average PW values expected to increase in
size day 3 across the Southern to Central Plains, into the Upper
MS Valley in a region of strengthening south southwesterly to
southwesterly low to mid level flow. There is the likelihood of
numerous shortwaves moving northeastward in this mid level
southwesterly flow across the mid section of the nation, supporting
increasing precip chances/coverage across this region. There still
is a large spread in the models with respect to placement of max
qpf, leading to low confidence at the moment for the day 3 time
period. Given the model spread and dry antecedent soil moisture and
high FFG values, the risk area was maintained at marginal, with
the potential for upgrade to slight in subsequent model cycles if
better agreement with max qpf axes occurs.


Oravec
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 100808
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
408 AM EDT Fri Apr 10 2026

Day 1
Valid 12Z Fri Apr 10 2026 - 12Z Sat Apr 11 2026

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

A west-east orientated frontal boundary will be dropping southward
through the period while PW values of +2-2.5 standard deviations
advect northward across the region as the low level flow
strengthens. Meanwhile, shortwave energy pushing northeastward
into this high PW axis in the vicinity of this front will support
areas of slow moving convection along this front, locally heavy
rains and isolated runoff issues. HREF neighborhood probabilities
show 40-70% for 2 inches and 20-40 % for 3 inches of rainfall
across these areas. While areal averages are generally expected to
be less than 1.5 inches, there are signals for isolated maximums of
3-4+ inches per the latest CAM guidance. The Marginal Risk area for
excessive rainfall was maintained from the Oklahoma/Texas
Panhandles to southwest Missouri.

Campbell


Day 2
Valid 12Z Sat Apr 11 2026 - 12Z Sun Apr 12 2026

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

Gulf moisture will continue to advect northward with PW anomalies
surging to +3 deviations above seasonal normal across the Plains.
Upper dynamics will support ascent ahead of a longwave trough
entering the West Coast, as well as a shortwave trough traversing
the High Plains. As ridging builds in across the east, this will
also promote strong southerly flow and a low level jet over the
Southern Plains and Texas to advect moisture and instability in the
area. At the surface, a dry line across West Texas will help serve
as an initiating mechanism for convection. The latest guidance
continues to depict a signal for 2-4 inches possible from the
Concho Valley in West Texas to the Red River Valley in southern
Oklahoma. Rainfall rates could also be as high as an inch or two
per hour with organized convection likely as noted with SPC's
Slight Risk across the region. WPC maintained the Slight Risk for
excessive rainfall from the West Texas/Hill Country northeast to
the Red River Valley. A Marginal extends from the Rio Grande to
southeast Kansas.

Campbell/Wilder


Day 3
Valid 12Z Sun Apr 12 2026 - 12Z Mon Apr 13 2026

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTHERN PLAINS AND LOWER MISSISSIPPI VALLEY...

Multiple rounds of strong to severe storms will persist across the Southern/Centrals Plains and Lower Mississippi Valley given
favorable wind shear and instability in place. Moisture transported northward from the western Gulf to the Midwest between the eastern U.S.
upper ridge and the trough over the Rockies will maintain enhanced
rainfall. And with limited eastward progression of the QPF
footprint expected during this period, it will keep an elevated
threat for local flash flooding concerns. A Marginal Risk remains
in effect from central-eastern Texas to southeast Kansas/southwest
Missouri.

Campbell

$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 111243
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
843 AM EDT Sat Apr 11 2026

Day 1
Valid 1227Z Sat Apr 11 2026 - 12Z Sun Apr 12 2026

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

...Central Plains...

A persistent MCS responsible for periods of excessive rainfall and
resulting flash flooding will continue through the remainder of
this morning. The 12Z TOP sounding shows as much as 1,000 J/kg of
MUCAPE, along with a saturated and nearly 8,000ft warm cloud layer
aloft, plus a highly sheared environment featuring excellent low-
level SRH in the sfc-1km layer that exceeds 250 m2/s2. The ARW has
handled this complex the best and it suggests organized
thunderstorms for at least a few more hours over northeast KS that
could expand into far northwest MO. WPC MPD #0090 has been
highlighting the threat, but with several more hours of excessive
rainfall expected to continue deeper into the day, WPC has upgraded
portions of the Central Plains to a Marginal Risk for additional
flash flooding today.

Mullinax


---Previous Discussion---

...Southern Plains...

The presence of an increasing southerly low level will transport
Gulf moisture northward and pool over the Plains and Mississippi
Valley as an upper level trough enters the West and ridging builds
over the East. Meanwhile the upper dynamics and embedded shortwave
energy will support ascent ahead of a longwave trough. At the
surface, a dry line across West Texas will help serve as an
initiating mechanism for convection in the afternoon. Strong to
severe thunderstorms are expected to fire up over the Southern and
Central High Plains, migrating eastward eventually making headway
into the adjacent Concho Valley and lower Trans Pecos. As cells
merge due to cold pool mergers and low-level jet initiation, a
large cluster of heavy rainfall will ensue through the rest of
Saturday night into Sunday morning.

General consensus maintains 2-4 inches possible from the Concho
Valley in West Texas to the Red River Valley in southern Oklahoma.
Neighborhood 24 hr QPF HREF probabilities show a strong signal for
50-80% for 2 inches for this region and 40-70% for 3 inches. A
Slight Risk for Excessive Rainfall remains in effect across
portions of the Southern Plains, especially the areas referenced above.

...Upper Midwest and Great Lakes...

Scattered to widespread convection is expected across parts of
Wisconsin and Michigan as moisture increase along a warm front
lifting northward through the region. Areal averages of around 1
inch are still on track. Much of the region will be sensitive to
additional precipitation as there has been ongoing snow melt and
high river flows. Although it may be isolated, flash flooding
may be possible during this period. A Flood Watch remains in effect
across the Michigan U.P. and far northern Lower Michigan and Wisconsin.

...Northeast Kansas to the Missouri/Iowa border...

Ongoing convection from overnight is producing some decent rainfall
rates from northeast Kansas to northern Missouri. Most of the
guidance show convection dying down during the morning hours and
diminished by 18Z. There is a non zero chance that there may be
very isolated heavy rainfall that could lead to localized flash flooding.

Campbell


Day 2
Valid 12Z Sun Apr 12 2026 - 12Z Mon Apr 13 2026

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR CENTRAL TEXAS...

...Central Texas...

Multiple rounds of strong to severe storms will persist across the Southern/Central Plains and Lower Mississippi Valley given high
moisture presence, favorable wind shear and instability in place.
A meandering dry line across the region will provide a focus for
backbuilding cells. With limited eastward progression of the QPF
footprint expected during this period, there is a growing threat
for flash flood concerns across portions of Hill Country to the I-35
corridor south of Dallas. A Slight Risk for Excessive Rainfall is
now in effect for central Texas for the threat with a Marginal Risk
extending northeastward through Oklahoma and adjacent areas of Kansas/Missouri/Arkansas.

...Northern Michigan...

Gulf moisture will continue to transport northward and interact
with the frontal boundary draped across the region. An additional 1
to 2 inches of rain is expected across the upper portion of the
Mitten which may expedite local snow melt and runoff. A Marginal
Risk for Excessive Rainfall remains in effect across northern Michigan.

Campbell/Wilder


Day 3
Valid 12Z Mon Apr 13 2026 - 12Z Tue Apr 14 2026

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE UPPER MISSISSIPPI VALLEY AND UPPER GREAT LAKES REGION...

Showers and thunderstorms will persist through this period as the
warm front lifts into southern Canadian and the cold front advances
through the Northern Plains into the Upper Mississippi Valley.
Additional rainfall will maintained an elevated threat for isolated
flash flooding and speed up snow melt around the region. A Marginal
Risk remains in effect from eastern Minnesota to northern Michigan.


Campbell
$$

--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 120810
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
410 AM EDT Sun Apr 12 2026

Day 1
Valid 12Z Sun Apr 12 2026 - 12Z Mon Apr 13 2026

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR CENTRAL TEXAS...

...Central Texas...

Broad troughing in the west will continue to direct sheared 500mb
vorticity maxima at the Southern Plains as a narrow 250mb jet
streak over the Central Plains places its divergent right-entrance
region over central and southern TX. Between the trough in the West
and high pressure over the Southeast, a strong IVT exceeding 500
kg/m/s will engulf much of the Southern Plains with 1,000-2,000
J/kg of MLCAPE. Convection will fire up along and ahead of the
dryline during the afternoon and evening hours. Vertical wind
shear and low-level helicity will be sufficient to support strong-
to- severe storms, but the uncertainty lies in the orientation of
surface troughs and outflow boundaries that reinvigorate storms
Sunday night, and where they are located. Some CAMs show some more
progressive segments of storms, while others show potential for
back-building and training.

12Z HREF guidance, specifically 24-hr QPF probabilities, show
moderate chances (40-60%) for rainfall totals >2", with the bulk of
the rainfall coming after 18Z and before 12Z Sunday. There are some
low chance probabilities (20-30%) along I-35 from San Antonio to
Austin. Southern and eastern TX badly need rainfall (UNL drought
monitor shows severe drought in many places), but excessive
rainfall rates approaching 2"/hr over very dry/hard ground can
become hydrophobic. Add in the metro areas at risk (I-35 corridor)
and the inherited Slight Risk still looks to be on track.

The expansive area of anomalous moisture (>90th climatological
percentile per NAEFS) extends as far north as eastern OK, southeast
KS, and southwest MO. Excessive Rainfall in these areas will be
largely driven by the aforementioned 250mb jet streak as southerly
850mb winds inject the moisture into this divergent setup aloft.
Soundings are not as saturated and storm motions are faster, thus
supporting the Marginal Risk currently in place.

...Northern Michigan...

A Marginal Risk remains in effect for this period. Anomalous Gulf
moisture pumping northward will interact with the draped frontal
boundary to bring enhanced rainfall to the region. NAEFS continue
to show PWs and IVT values that are above the 99th climatological
percentile that features a combination of saturated soils and
lingering snowpack. Accumulations of 1 to 2 inches are anticipated
for the northern half of Mitten which may cause any lingering
snowpack to melt and possibly exacerbate the flooding potential on
Sunday.

Campbell/Mullinax


Day 2
Valid 12Z Mon Apr 13 2026 - 12Z Tue Apr 14 2026

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE UPPER MISSISSIPPI VALLEY AND UPPER GREAT LAKES REGION...

Another round of showers and thunderstorms will move through the
Upper Mississippi Valley and Great Lakes during the afternoon and
evening hours, prolonging the threat for excessive rainfall,
increased snow melt and flash flooding. A Marginal Risk
remains in effect from eastern Minnesota to northern Michigan.

Campbell


Day 3
Valid 12Z Tue Apr 14 2026 - 12Z Wed Apr 15 2026

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FROM THE TEXAS
HILL COUNTRY TO THE UPPER MIDWEST/GREAT LAKES REGION...

Multiple rounds of strong to severe thunderstorms expected from
Texas to the Midwest states, given favorable wind shear and
instability in place as multiple impulses eject across the Plains.
Gulf moisture will be funneling northward between the trough over
the Rockies and the ridge over the eastern states. The environment
will be favorable for a few mesoscale convective systems to
develop and the limited eastward progression will likely result in
areas that have excessive rainfall leading to some instances of
flash flooding. A Marginal Risk area span from the Texas Hill
Country northeastward to the Midwest and western Great Lakes.

Campbell
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 130756
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
356 AM EDT Mon Apr 13 2026

Day 1
Valid 12Z Mon Apr 13 2026 - 12Z Tue Apr 14 2026

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE UPPER MISSISSIPPI VALLEY AND UPPER GREAT LAKES REGION...

A Marginal Risk for excessive rainfall was maintained for this
period from eastern Minnesota to Lower Michigan. Although there was
a modest decrease in the neighborhood probabilities for >1" totals,
there still 20 to 40% across eastern Wisconsin and western
Michigan as a formidable LLJ and increasing convergence within a
progressing warm front could very well maximize the potential for
heavier precip. Some rivers and streams across the region have
ongoing minor flooding and any additional rainfall could speed up snow melt.

Campbell/Kleebauer


Day 2 Valid 12Z Tue Apr 14 2026 - 12Z Wed Apr 15 2026

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FROM THE TEXAS
HILL COUNTRY TO THE UPPER MIDWEST/GREAT LAKES REGION...

A developing upper jet coupling will likely aid in regional ascent
with fairly generous instability axis situated from the Corn Belt
to the southern Great Lakes and points south. Multiple areas of
convection expected for this period from the Southern Plains to the
Upper Midwest/Great Lakes region. The main area of focus will be
over the Midwest where guidance is depicting several hours of cells
producing up to 1.5 inches/hr rainfall rates from Iowa to western
New York and SPC has identified this part of the country as having
an Enhanced Risk for severe weather that includes the potential for
damaging winds, very large hail and tornados.

Meanwhile convection will fire up ahead of the dryline and
approaching cold front across the Plains. The environment will be
favorable for a few mesoscale convective systems to develop and the
limited eastward progression will likely result in areas that have
excessive rainfall leading to some instances of flash flooding. A
Marginal Risk area span from the Texas Hill Country northeastward
to the Midwest and western Great Lakes. SPC has highlighted much
of the same area as having a Slight Risk for severe thunderstorms.

Campbell/Kleebauer


Day 3
Valid 12Z Wed Apr 15 2026 - 12Z Thu Apr 16 2026

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FROM TEXAS TO
THE UPPER MIDWEST/GREAT LAKES REGION...

The overall setup will be very similar for this period just
shifted a bit to the east. SPC continues to have a Slight Risk for
severe thunderstorms capable of producing damaging winds, large
hail and a potential for tornadoes while WPC maintains a Marginal
Risk for excessive rainfall from eastern Texas to the Midwest/Great
Lakes region. Areal averages will generally be less than 1.5
inches but a few locations may exceed 1.75 inches. Guidance still
has a fair amount of r spread on where some of the highest amounts
will occur but consensus is hinting southeast Oklahoma to the Ozark
mountains with a secondary focus from central Illinois to northwest Ohio.

Campbell
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 140826
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
426 AM EDT Tue Apr 14 2026

Day 1
Valid 12Z Tue Apr 14 2026 - 12Z Wed Apr 15 2026

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL ACROSS THE CENTRAL
L.P. OF MICHIGAN AND SOUTHEAST WISCONSIN...

...Great Lakes Region...

A Slight Risk for excessive rainfall remains in effect for portions
of the Great Lakes region. A shortwave/vorticity center lifting
out over the mean ridge in the Great Lakes region will drive
stronger confluence of the low level jet across Iowa to trigger another
round of strong to severe thunderstorms Tuesday evening. Overall
deep layer steering flow and fairly orthogonal ascent over boundary
should help to focus a similar west to east (WNW to ENE) oriented
axis of training thunderstorms. Upper-level dual jet couplet will
further enhance up-scale growth to a broader complex to maintain
through the overnight period. Most of the area remains at near or
above record spring rainfall and soils are fairly saturated, so
with cells capable of 1.5-2"/hr rates and localized totals of 2-3+"
suggest the placement of a Slight Risk of Excessive Rainfall
across portions of eastern WI and central MI (along and north of I-94).

...Pecos River Valley through Southern Plains into Ozark Plateau...

A steady stream of PW values of 1.25 to 1.5 inches will be
advecting northward through the Southern/Central Plains nearly
parallel to the dryline. This will be conducive for slow storm
motion with locally heavy rainfall. Consensus suggests 3 to 4
inches possible within the isolated cells. The Marginal Risk area
is connected to the area of concern over the Great Lakes and just
note the coverage will decrease northward along the dry-line.

Campbell/Gallina


Day 2
Valid 12Z Wed Apr 15 2026 - 12Z Thu Apr 16 2026

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FROM TEXAS TO
THE UPPER MIDWEST/GREAT LAKES REGION...

The surface to mid-level environment remains very similar to the
prior 3 days, with a stark dry line extending from the Pecos River
Valley across the Southern Plains into the Upper Mississippi
Valley. During this period the longwave trough will finally be
making progress toward the Central Plains albeit as it begins to
weaken and the deep layer moisture axis and instability shift
slightly eastward. Thunderstorms are expected to break out with
hourly rates pulsing up to 2 inches/hr. Some locations ahead or
along the frontal boundary may receive over 3 inches between the
Ozarks Plateau and northeast Texas.

Further north, the environment over the Midwest/Great Lakes region
will have notably less moisture and instability present then the
days prior, however additional rains will maintain an elevated
threat for localized flooding over the hydrologically
sensitive/saturated areas of the northern Great Lakes region. The
most favorable location for appreciable precipitation will be from
northeast Illinois to souther Michigan. The Marginal Risk area was
maintained and in spans from northeast Texas northward to
Wisconsin/Lower Michigan and east to western New Yorks and Pennsylvania.

Campbell/Gallina

Day 3
Valid 12Z Thu Apr 16 2026 - 12Z Fri Apr 17 2026

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

Campbell
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 150803
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
403 AM EDT Wed Apr 15 2026

Day 1
Valid 12Z Wed Apr 15 2026 - 12Z Thu Apr 16 2026

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR THE GREAT=20
LAKES AND NORTHERN OHIO VALLEY..

Showers and thunderstorms will continue to focus near the west-east
orientated frontal boundary draped across the Ohio Valley/Great
Lakes region into the Northeast as a weak surface low traverses the
boundary and intersects the abundant moisture and instability. Meanwhile,
the longwave trough will finally be making progress toward the=20
Central Plains and the deep layer moisture axis and instability=20
shifts slightly eastward. This setup will be conducive for periods
of heavy rainfall. Models are suggesting areal averages of 1 to 3
inches occurring with some overlap with rainfall footprint from
prior days. The Slight Risk remains in effect from northern=20
Illinois to souther Michigan and northwest Ohio to account for=20
uncertainty on storm track and the spread of 2 inch HREF 24 hr QPF=20 neighborhood probability.

...Eastern Oklahoma and the Ozarks...

Convection is expected to become more active during the afternoon
and track generally from the southwest to northeast ahead of the
approaching trough. Eastern Oklahoma into the Ozarks will be in=20
the right entrance of the jet streak, which will help provide lift.
At the surface, high PWATS and surface instability will once again
prime the atmosphere for hourly rainfall rates of an inch/hr. QPF=20
guidance does show a maximum of 1-2 inches across the region, but=20
model guidance shows little to no probability for accumulations=20
exceeding 2 inches. Therefore, a Marginal Risk is maintained for=20
the risk area. Additionally, the more flash flood prone Ozark=20
mountain range is relatively dry.

...Northeast...

Remnants of the storms across the Great Lakes may bring a round of
showers and storms in the morning, followed by another round of=20
heavier showers and thunderstorms in the afternoon. Model guidance=20
shows a corridor of 1-1.5 inches rainfall with embedded higher=20
amounts depending on the model. The relatively lower flash guidance
across western Pennsylvania and the more urban footprint of areas=20
such as Connecticut and New England also help confidence of=20
expanding the Marginal eastward.

Campbell/Wilder


Day 2
Valid 12Z Thu Apr 16 2026 - 12Z Fri Apr 17 2026

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

Campbell


Day 3
Valid 12Z Fri Apr 17 2026 - 12Z Sat Apr 18 2026

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR NORTHERN
MISSOURI, EASTERN IOWA AND NORTHWEST ILLINOIS...

A band of weakening showers and thunderstorms will pass through=20
the Ohio Valley with the lead shortwave trough. Meanwhile the long
wave trough approaching the Midwest will have better large scale=20
ascent and instability to yield better areal coverage of QPF with a
more focused swath of higher amounts across Missouri to the
Illinois/Wisconsin border. The previous Slight Risk area was
positioned more over Iowa and Wisconsin, however the latest trends
suggest a modest south/southeast adjustment to northern Missouri,
eastern Iowa, northwest Illinois and extreme southwest Wisconsin.=20
will be valid from northern Missouri to southwestern Wisconsin for=20

Campbell
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 160809
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
409 AM EDT Thu Apr 16 2026

Day 1
Valid 12Z Thu Apr 16 2026 - 12Z Fri Apr 17 2026

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

Campbell


Day 2
Valid 12Z Fri Apr 17 2026 - 12Z Sat Apr 18 2026

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF=20
THE MID-MISSISSIPPI VALLEY INTO THE SOUTHERN PLAINS...

A deep, positively-tilted longwave trough advancing into the Plains
will promote broad areas of ascent from the Southern Plains to the
Midwest. A well-defined axis of diffluence ahead of the mean=20
trough with several shortwaves rippling through the flow will=20
enhance an area of convective development within a strengthening=20
warm-sector environment positioned between a strong cold front over
the High Plains and a quickly advancing warm front migrating=20
poleward through the adjacent Mississippi and Ohio Valleys. This
environment will be rather favorable for a broad footprint for
heavy rainfall. There has been a persistent south/southwest trend
with the axis of highest QPF for several model cycles which now
focuses over northeast Oklahoma to north-central Missouri with
areal averages of 1-2 inches with isolated maximums nearing 3+
inches. The adjusted Slight Risk spans from northeast Oklahoma to
northern Illinois with the encompassing Marginal Risk from the
Oklahoma.Texas border northward to Wisconsin.

Campbell/Kleebauer


Day 3
Valid 12Z Sat Apr 18 2026 - 12Z Sun Apr 19 2026

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL FOR PORTIONS OF
THE SOUTH, LOWER MISSISSIPPI VALLEY AND TEXAS...

The frontal system described above will continue to advance
eastward with the trailing tail of the cold front dropping
south/southeast through Texas and the Lower Mississippi Valley.
Gulf moisture will be advecting northward into the Southern Plains
and pooling across Texas. PW values of 1.25-1.5 inches will be present
over much of eastern Texas and Louisiana during this period. Strong
convergence will lead to showers and thunderstorms focusing along
and ahead of the frontal boundary, especially for the later half of
the period. Areal average of 1 to 2 inches expected with hourly
rainfall rates greater than 1 inch/hr as well may lead to isolated
areas with flash flooding concerns. A Marginal Risk area is in
effect from South Texas to northern Mississippi.

Campbell
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 170746
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
346 AM EDT Fri Apr 17 2026

Day 1
Valid 12Z Fri Apr 17 2026 - 12Z Sat Apr 18 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM OKLAHOMA
THROUGH PORTIONS OF THE MIDWEST...

A strong cold front tracking southeast across the Plains will run
into a moist and unstable air mass driven by a robust low level jet
streaming north off the western Gulf and into the Great Lakes.
Meanwhile, a strengthening upper level jet will develop across
Texas and Oklahoma Friday night that will further enhance lift
across the Slight Risk region, particularly the southern part of
it. The result will be a series of waves of strong thunderstorms
that will feed on the influx of moisture and instability to allow
for frequent redevelopment and training as the entire complex of
storms pushes southeast. The strongest storms and most persistent
rainfall will occur over areas hard-hit in recent days with prior
heavy rainfall, so soils in areas from southern Oklahoma to western
Missouri are already near saturation and well above normal for soil
moisture content for this time of year. Urban areas from Kansas
City to Tulsa will be especially vulnerable should persistent heavy
rains set up over those metro areas. Meanwhile, a portion of the
Ozarks could also introduce a topographic factor to any flooding
potential. A higher-end Slight (25-40% chance of flash flooding)
is in effect from northwestern Oklahoma through central Missouri.

Meanwhile, further north into the Midwest, the storms are more
likely to organize into a single line of storms more quickly.
However, these areas have even more saturated soils due to more
recent rains. When added the urban factor in cities such as St.
Louis, Chicago, and Milwaukee, even a shortened period of heavy
rainfall could still result in widely scattered instances of flash
flooding. The Slight Risk in this area was expanded north up Lake
Michigan to Green Bay, but elsewhere remains little changed.

Wegman


Day 2
Valid 12Z Sat Apr 18 2026 - 12Z Sun Apr 19 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE GULF COAST AND LOWER MISSISSIPPI VALLEY...

A strong cold front sweeping south down the Plains will provide the
primary forcing for a line of strong thunderstorms to form as the
front uplifts a warm and moisture-laden air mass from the Gulf. Due
to close proximity to the Gulf, PWATs are likely to spike to
between 1.5 and 1.75 inches Saturday evening. This will support
thunderstorms capable of very heavy rainfall. The line will
generally be progressive, moving south. Further, the Marginal Risk
area is generally covering some of the highest FFG areas in the
country. Thus, the flash flooding threat is largely focused on the
urban factor in areas such as Houston, Beaumont, and Alexandria.
Most of the convective activity is expected at or after sunset, so
any flooding that occurs will be more dangerous.

Wegman


Day 3
Valid 12Z Sun Apr 19 2026 - 12Z Mon Apr 20 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR DEEP SOUTH
TEXAS...

An area of disturbed weather, partially from the remnants of a cold
front that swept across much of Texas on Saturday, will impact
portions of Deep South Texas Sunday into Sunday night. The air mass
will be characterized by summer-like amounts of moisture, with
PWATs exceeding 2 inches in a few areas, and over 1.75 inches
across much of Deep South Texas. This will support any showers and thunderstorms that form across the area to be capable of very
heavy rainfall. However, the forcing for this rainfall will be
lacking, resulting in only isolated to widely scattered showers and thunderstorms. Further, the FFGs in Deep South Texas are quite
high, so any storms, which should be slow-moving, would need to
train or remain over a single area for a while to produce flash
flooding. Thus, only isolated instances of flash flooding are expected.

Wegman
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 180658
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
258 AM EDT Sat Apr 18 2026

Day 1
Valid 12Z Sat Apr 18 2026 - 12Z Sun Apr 19 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE GULF COAST AND LOWER MISSISSIPPI VALLEY AS WELL AS FOR PORTIONS
OF THE MID-ATLANTIC...

...Gulf Coast and Lower Mississippi Valley...

A cold front sinking south across Texas on Saturday will run into
an increasingly moist and unstable air mass located along the Gulf
Coast Sunday afternoon. As the front lifts that air mass, rounds of
showers and thunderstorms are expected to form and roughly parallel
I-10 from near San Antonio east through southwestern Louisiana. The
potential for multiple rounds of heavy rain across urban areas,
particularly Houston, could result in isolated instances of flash
flooding. Recent dry weather across southeast Texas and especially
into Louisiana and southern Mississippi should work to limit the
flash flooding potential there, whereas across central Texas, soils
are a bit wetter from more recent heavy rainfall. Thus, FFGs
precipitously increase with eastward extent along I-10. The
inherited Marginal Risk was trimmed on the northern side, as the
most persistent thunderstorms are likely to focus further south
towards the Gulf Coast. The Marginal was expanded a bit west down
I-10 towards San Antonio due to the aforementioned more favorable
soil conditions.

...Mid-Atlantic...

A progressive line of thunderstorms associated with a fast-moving
cold front will sweep eastward across northern Pennsylvania and
western and central New York this afternoon and evening. The
Marginal was introduced primarily because preexisting moist soil
conditions across this region and the topography will both support
the development of isolated instances of flash flooding despite
less than impressive rainfall totals across this area. The line of
storms will traverse the Marginal Risk region at peak heating late
afternoon through the evening, which should allow the storms to
also be at their peak in strength.

Wegman


Day 2
Valid 12Z Sun Apr 19 2026 - 12Z Mon Apr 20 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTH TEXAS...

The cold front from Saturday night should be just off the coast
and into the Gulf Sunday morning, although a residual inverted
trough extending from the tail of this front is expected to linger
across South Texas much of the period. As the day progresses, weak
shortwave energy embedded within a shallow southern stream trough
will emerge from Mexico to produce modest ascent through divergence
and PVA, combining with convergence along the aforementioned
trough to create scattered showers and thunderstorms across the
region. Downstream of this feature, subtle ridging will halt the
progression of the surface trough, while additionally keeping PWs
pooled across South Texas, which is reflected by NAEFS ensemble
tables indicating that PWs will remain above the 90th percentile of
the CFSR climatology.

The overlap of this ascent into the moist column will manifest as
heavy rain producing convection, with both HREF and REFS indicating
a low end potential for 1"/hr rainfall rates. While the high-res
simulated reflectivity still features wide variation in coverage,
making confidence in the excessive rainfall potential a bit lower
than usual, storm motions within any of this convection will likely
be slow (0-6km mean winds of just 5-10 kts), so any of these heavy
rates could be sufficient to overcome the FFG. The greatest
potential may be along the immediate coast due to the overlap of
slower storms (pinned) and lower FFG, but anywhere these slow
storms develop, isolated instances of flash flooding could result.

Weiss


Day 3
Valid 12Z Mon Apr 20 2026 - 12Z Tue Apr 21 2026

...THERE IS A MARGINAL CHANCE OF EXCESSIVE RAINFALL ACROSS PARTS OF
NORTHERN CALIFORNIA AND ACROSS THE LOWER-MIDDLE TEXAS COAST TO THE
HILL COUNTRY...

...Northern California...

Deepening upper level low eventually closes off late in the weekend
off the northern CA coast. Afterwards, the guidance shows this
broad, deep low pinwheeling slowly eastward on day 3, thereby
allowing for a prolonged period of favorable forcing, i.e. upper diffluence/deep layer ascent and anomalous low-mid layer moisture
transport. The latest GEFS in fact indicates 850-700 mb moisture
flux peaking between 2-3 standard deviations above normal from the
Bay area into the northern CA coastal ranges and Sacramento Valley.
Due to the nature of the upper system (closed mid-upper low), this
will not be a typical AR event, per the 'weak' AR classification
from CW3E. However, Integrated water vapor transport (IVT) values
do peak around 500 Kg/m/s, while the guidance (GFS-ECMWF-NAM) does
indicate elevated CAPEs of 100-250 J/Kg. Areal average QPFs per the
guidance on Day 3 (12Z Mon-12Z Tue) support widespread 1-2"
rainfall totals, though higher-res members (including the RRFS) do
show isolated higher totals closer to 3". Given the potential for
at least 0.50"/hr rainfall rates on Day 3, the Marginal Risk area
was maintained (and expanded) to account for the possibility of
some excess runoff over burn scars.

...Lower-Middle Texas Coast to the Hill Country...

Guidance continues to show subtle/flat southern stream shortwave
traversing this area Mon-Mon night, which will likely become
convectively-aided from any MCV(s) emanating out of northeast
Mexico. Uptick in deep-layer forcing along with moisture pooling
from the western Gulf (PWs increasing to 1.7-1.8") and some, albeit
weak instability (MUCAPEs ~500 J/Kg) will lead to a more favorable
environment for widespread rainfall with embedded heavier cores. We
maintained the Marginal Risk area inherited from yesterday's Day 4
ERO, while expanding a little farther north to include parts of the
Hill Country based on the latest guidance trends (deterministic and probabilistic QPF). In addition, the latest ECMWF Extreme Forecast
Index (EFI) for QPF peaks between 0.6-0.7 during this event, with
a shift-of-tails close to 1 along the coast.

Hurley
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 190745
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
345 AM EDT Sun Apr 19 2026

Day 1
Valid 12Z Sun Apr 19 2026 - 12Z Mon Apr 20 2026

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

In coordination with CRP/Corpus Christi, TX and EWX/San Antonio, TX
forecast offices, the inherited Marginal Risk across Deep South
Texas was removed with this update. While there will be high
moisture content (PWATs around 1.75 inches) and slow moving cells
due to light steering winds across Deep South Texas, the lack of
instability and very high FFGs will effectively squelch any flash
flooding threat. MUCAPE values will struggle to exceed 300 J/kg
through the day, which is simply not enough instability to generate
the rain rates necessary to exceed the high FFGs.=20

Wegman


Day 2
Valid 12Z Mon Apr 20 2026 - 12Z Tue Apr 21 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
NORTHERN CALIFORNIA...

...Northern California...

A large upper level cutoff low located off the coast will drift
eastward into northern California on Monday. The cutoff low will
not have a connection to the tropics, which will limit both amount
of moisture and any instability that can be transported into
northern California. Despite that, as is typical of cutoff lows,
the movement will be slow, which could allow for an extended
duration of light to moderate rainfall. That rain will impact an=20
area that has burn scars, urban areas (Bay Area), and steep terrain
which favors localized flash flooding. Thus, the Marginal Risk is
left unchanged with this update.

...South Texas...

The inherited Marginal Risk over a portion of this area was
removed with this update, in coordination with CRP/Corpus Christi,
TX, EWX/San Antonio, TX, and HGX/Houston, TX forecast offices. As
on Day 1/Sunday, the limiting factor once again will be a true lack
of instability, with MUCAPE values again struggling to exceed a
couple hundred J/kg anywhere in Texas. Thus, despite above normal
atmospheric moisture, and below normal forward motions for any
cellular convection that does form, the high FFGs and limited
rainfall rates should continue to prevent any flash flood development.

Wegman


Day 3
Valid 12Z Tue Apr 21 2026 - 12Z Wed Apr 22 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
CALIFORNIA AND SOUTHEAST TEXAS...

...California...

A cutoff large upper level low over the coast Tuesday morning will
progress east/inland through Tuesday night. This will direct the
southwesterly onshore flow further south and east across central
California. A pocket of instability with MUCAPE values as high as
500 J/kg may move into central California during the day Tuesday as
well. The primary forcing however will remain the steep slopes of
the Sierras, where the greatest rainfall rates and amounts are
expected. Due to the instability however, the more populous valley
locations may also see periods of heavier rains, including across
the Bay area and Sacramento. Burn scars and heavier rains into some
of the coastal ranges and western Transverse Ranges could also
result in localized flash flooding. Thus, the inherited Marginal
risk was expanded south down the coast to Santa Barbara, while the
Marginal in central California was left unchanged with this update.

...Southeast Texas...

The Marginal Risk across southeast Texas was adjusted a bit to the
northeast from inherited in keeping with the latest trends in the
guidance, suggesting increased potential for heavier rains into the
Houston area, and decreased potential around Corpus Christi. Unlike
both Sunday and Monday, by Tuesday there's better agreement that
the primary limiting factor, instability, will be less of a
limiting factor. MUCAPE values are expected to rise above 1,000
J/kg across much of the MRGL risk area. Somewhat more saturated
soils in the Houston area as a result of yesterday's rains could
also have some lingering effects into Tuesday. Thus, the inherited
Marginal was left largely unchanged with this update.

Wegman
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 200804
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
404 AM EDT Mon Apr 20 2026

Day 1
Valid 12Z Mon Apr 20 2026 - 12Z Tue Apr 21 2026

...THERE ARE MARGINAL RISKS FOR EXCESSIVE RAINFALL FOR PORTIONS OF
NORTHERN CALIFORNIA AND SOUTHCENTRAL TEXAS...

...Northern California...

A large upper level cutoff low located off the coast will drift
eastward into northern California today. The cutoff low will not
have a connection to the tropics, which will limit both amount of
moisture and any instability that can be transported into northern
California. Despite that, as is typical of cutoff lows, the
movement will be slow, which could allow for an extended duration
of light to moderate rainfall. That rain will impact an area that
has burn scars, urban areas (Bay Area), and steep terrain which
favors localized flash flooding. Thus, the Marginal Risk is left
unchanged with this update.

...Southcentral Texas...

A new Marginal Risk was reintroduced for a portion of Southcentral
Texas with this update in coordination with EWX/San Antonio, TX
forecast office. A subtle shortwave in the upper levels will add
forcing to an already highly moist environment with relatively slow
storm motions. Instability will be the primary limiting factor for
heavy rainfall rates, but the shortwave is expected to overcome
that instability a bit with the increased forcing. This solution is
depicted in several of the CAMs, which show a series of training
storms developing well after sundown, and tracking slowly eastward
across Southcentral Texas. Many of those CAMs highlight the storms
tracking right over the San Antonio metro area. The primary flash
flooding threat involves urban concerns in the San Antonio metro
Monday night.

Wegman


Day 2
Valid 12Z Tue Apr 21 2026 - 12Z Wed Apr 22 2026

...THERE ARE MARGINAL RISKS FOR EXCESSIVE RAINFALL FOR PORTIONS OF
CALIFORNIA AND SOUTHEAST TEXAS...

...California...

A cutoff large upper level low over the coast Tuesday morning will
progress east/inland through Tuesday night. This will direct the
southwesterly onshore flow further south and east across central
California. A pocket of instability with MUCAPE values as high as
500 J/kg may move into central California during the day Tuesday as
well. The primary forcing however will remain the steep slopes of
the Sierras, where the greatest rainfall rates and amounts are
expected. Due to the instability however, the more populous valley
locations may also see periods of heavier rains, including across
the Bay area and Sacramento. Burn scars and heavier rains into some
of the coastal ranges and western Transverse Ranges could also
result in localized flash flooding. The forecast remains on track
across California, and no changes were made. However, increases in
forecast rainfall along the Sierras in the Central Valley may
require a Slight Risk upgrade with future updates.

...Southeast Texas...

The Marginal Risk across southeast Texas remains unchanged with
this update. Onshore flow of deep Gulf moisture will advect across
southeast Texas along the periphery of a large area of high
pressure across the Southeast. MUCAPE values are expected to rise
above 1,000 J/kg across much of the MRGL risk area. Slow-moving and
training thunderstorms could cause isolated instances of flash
flooding, especially in urban areas such as Houston.

Wegman


Day 3
Valid 12Z Wed Apr 22 2026 - 12Z Thu Apr 23 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHEAST TEXAS AND SOUTHWEST LOUISIANA...

Persistent onshore flow of deep Gulf moisture and instability will
continue into southeast Texas and southwest Louisiana on Wednesday.
This is a continuation of the moist, unstable flow off the Gulf
from prior days, just drifted a bit to the east. Instability across
this region continues to increase compared to prior days, with
areas of over 2,000 J/kg in MUCAPE. Showers and thunderstorms will
continue to move northwestward amidst the southeasterly flow off
the Gulf. Urban areas such as Houston and Beaumont will have a
higher threat of isolated flash flooding, which will occur where
the storms with the heaviest rainfall rates are most persistent.

Wegman
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 220757
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
357 AM EDT Wed Apr 22 2026

Day 1
Valid 12Z Wed Apr 22 2026 - 12Z Thu Apr 23 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
SOUTHEAST TEXAS AND SOUTHWESTERN LOUISIANA...

Steady southerly flow off the Gulf will continue to advect a plume
of Gulf moisture northward across the Marginal Risk area. The flow
will not be much to write home about, generally between 5-15 kts=20
at 850 mb. In addition to the rather weak advection the upper=20
levels will become decidedly less favorable for widespread rain=20
across the region as ridging and associated subsidence build in.=20
Thus, there is good agreement that any heavy rains will be=20
disorganized and widely scattered in nature, as compared with the=20
rains further west across Texas the past couple days. Urban=20
concerns remain a driving factor for maintaining the Marginal.
Guidance has shifted a bit to the south and west with the threat
for a few cells capable of heavy rains. This resulted in the
Marginal being shifted west along I-10, over an area that has been
hard-hit with heavy rains in recent days. Meanwhile portions of the
Piney Woods of far eastern Texas were removed as guidance has
suggested any more organized cells will be confined to around the
I-10 corridor. The westward shift resulted in small trimming in
south-central Louisiana as well. Should there be greater than
expected organization from Houston west along I-10, a targeted
Slight Risk may need to be considered due to the saturated soils
from yesterday's and prior days' rainfall.

Wegman


Day 2
Valid 12Z Thu Apr 23 2026 - 12Z Fri Apr 24 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM NORTHEASTERN
OKLAHOMA THROUGH THE ARROWHEAD OF MINNESOTA...

A strong but slow-moving low will lurk north of North Dakota in
southern Manitoba Thursday and Thursday night. The leading cold
front associated with this low has consequently also slowed down
its forward speed in much of the guidance. The result has been an
increase in forecasted rainfall that will occur ahead of that cold
front as it uplifts a moist and unstable air mass with a 30-50 kt
LLJ. Since the front has slowed down, there's more time for
moisture to advect north with the LLJ into Iowa, Minnesota, and
Wisconsin. While portions of Minnesota and Wisconsin were hard hit
with heavy rains last week, there has been sufficient time for the
soils to dry out some and for the rivers to drain that rainfall.
Thus, conditions are at or even a bit below normal for soil
moisture. Despite that, potential for fast-moving but training
storms could still result in some "stripes" of heavier rainfall
that could cause isolated flash flooding, especially if urban
centers such as the Twin Cities are included. The inherited
Marginal was shifted west but expanded well to the north to include
some of these more vulnerable areas of Minnesota and Wisconsin with
this update. The good news is further south across Kansas and
Missouri, the forcing now doesn't look like it will be quite as
strong as the forecast looked 24 hours ago. Thus, while a Slight
Risk upgrade was considered for along the KS/MO border south of
Kansas City yesterday, confidence has increased that the current
Marginal Risk for that area will suffice.

Wegman


Day 3
Valid 12Z Fri Apr 24 2026 - 12Z Sat Apr 25 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE MIDDLE AND LOWER MISSISSIPPI VALLEY...

A slow-moving cold front will run into increasing Gulf moisture and
instability across the Middle and Lower Mississippi Valley on
Friday. Clusters of showers and thunderstorms will develop along
the front in northwestern portions of the Marginal across Arkansas
and southeastern Missouri with peak heating Friday afternoon. Those
storms will gradually progress south and east, with the potential
for localized training of stronger cells embedded within these
clusters of storms. Almost all of the Marginal Risk area is in an
area with extremely dry soils. Depending on the soil type, this
could make some of the soils (clays) start out the rainfall event
in a very hydrophobic state, which would support rapid runoff.
However, for most, all but the heaviest rains will be very
beneficial for this parched area of the country. Urban areas, areas
with hydrophobic soils, and poor-drainage areas will be at the
greatest risk for isolated instances of flash flooding. Smaller=20
drainage basins and the portions of Arkansas with the Ozarks=20
topographically confining any potential runoff to steep valleys
will also be at a locally higher risk for flash flooding.

Wegman
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 230746
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
346 AM EDT Thu Apr 23 2026

Day 1
Valid 12Z Thu Apr 23 2026 - 12Z Fri Apr 24 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL IN THE CENTRAL
PLAINS AND UPPER MIDWEST...

Convection is expected to blossom this afternoon along and ahead of
a cold front in the Central U.S. The warm sector ahead of the front
should be characterized by an overlap of moderate instability (1000
to 2000 j/kg MLCAPE) and anomalously high moisture content (1.0 to
1.5 inch PWATs; near or above the 90th percentile for late April).
The combination of instability and moisture should support heavy
rain rates in organized convection in excess of 1 inch per hour at
times. The main limiting factor for higher rainfall totals over the
entire forecast period, and any impacts from flash flooding, should
be a lack of persistence to the high rain rates in a given spot.

From the I-70 corridor to the north, lines of thunderstorms are
expected to be relatively narrow and steadily progress, given the
deep layer shear vectors will be oriented closer to perpendicular
with the cold front. Therefore, despite some pockets of lower flash
flood guidance (around or just under 2 inches in 3 hours), and
recent wet pattern in parts of the region, the heaviest rain rates
should not last very long and the flash flood risk is expected to
remain isolated. Furthermore, instability diminishes rapidly around
sunset, so rain intensity should drop off within about 6 hours of
convective initiation. It should be noted this assessment does not
necessarily apply to other flooding risks in the region: ongoing
mainstem river flooding, or potential for rain and snowmelt
flooding in the Upper Peninsula of Michigan. For more details on
those flooding hazards, refer to the National Water Center.

Further south, the pattern will be more supportive of backbuilding
and training convection, especially this evening and overnight from
southeast Kansas into northeast Oklahoma and the Ozark region of
southwest Missouri and northwest Arkansas. As the low level jet
veers and an upstream instability maximum persists in eastern
Oklahoma, hi-res models uniformly show a band of thunderstorms
becoming increasingly east-west oriented, more parallel to the deep
layer shear vector. Nevertheless, they all also show steady
progression to the southeast with some cold pool development, and a
lack of rainfall maxima in excess of 3 inches. Therefore, the risk
of flash flooding is currently expected to be isolated, but the
situation will be monitored in case a targeted Slight Risk is
needed later today.

Lamers


Day 2
Valid 12Z Fri Apr 24 2026 - 12Z Sat Apr 25 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL IN THE MID SOUTH...

A convective cluster or backbuilding convective line may be ongoing
on Friday morning -- most likely across northern Arkansas based on
00Z HREF EAS probabilities -- with the potential for additional
convective clusters to develop through the day across the region.
Updated WPC QPF places the heaviest rainfall across Arkansas,
northern Mississippi, and far northern Louisiana, and this is where
the Marginal Risk area was re-centered. There is some uncertainty
on where the heaviest rain will fall, as it should be tied in some
way to convective outflow from morning and early afternoon
activity. The warm sector to the south and southeast of that should
have a combination of moderate instability and precipitable water
close to 1.5 inches (around the 90th percentile for late April).
That sort of environment would support rain rates of 1 to 2 inches
per hour in organized convection, which could lead to isolated
flash flooding where backbuilding and training occurs.

Lamers


Day 3
Valid 12Z Sat Apr 25 2026 - 12Z Sun Apr 26 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL IN SOUTHEAST
KANSAS, SOUTHWEST MISSOURI, EASTERN OKLAHOMA, AND WESTERN ARKANSAS...

Available deep moisture in the southern Plains on Saturday should
be lower than prior days across the region, with model forecast
soundings indicating the potential for dry air from 800-600mb
associated with an elevated mixed layer. This would likely restrict
any excessive rainfall and flash flooding concerns to the isolated
variety. Nevertheless, strong instability and vertical wind shear
should support supercells evolving into convective lines. There is
not a consistent signal for concentrated areas of heavy rain, but
with the expected convective modes, localized areas of longer heavy
rain duration are possible via storm mergers and some upshear cell
development. Any corridors of heavy rain on Thursday or Friday
could also locally increase soil moisture and vulnerability to
another round of heavy rain. Therefore, the Marginal Risk was
maintained for Saturday and Saturday Night.

Lamers
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 240750
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
350 AM EDT Fri Apr 24 2026

Day 1
Valid 12Z Fri Apr 24 2026 - 12Z Sat Apr 25 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL IN THE MID SOUTH...

A convective line that had stalled over northern Oklahoma between
02Z and 06Z has recently shown signs of slow forward progress. This
increases confidence in the general evolution depicted in the 00Z
hi-res model guidance suite, which shows the line reaching northern
Arkansas and east-central Oklahoma by the start of the forecast
period at 12Z Friday, and continuing southeast through much of
central and eastern Arkansas through the daytime hours.

The end result should be an increasingly stable air mass and
widespread cloud cover over those same portions of Arkansas, and=20
adjacent southern Missouri and western Tennessee, associated with=20
gradually decaying convection, a cold pool and surface meso-high.=20
For these reasons, and trends to the southwest with the heaviest=20 precipitation in both hi-res and AI guidance, the Marginal Risk has
been shifted likewise. A reinvigoration of convection in the=20
afternoon and evening is most likely on the upshear flank of the=20
cold pool with west-southwesterly low level inflow and an upstream=20
reservoir of strong instability. The potential exists for periods=20
of training convection along and near the existing outflow boundary
(likely on the order of 1-3 hours), which may provide=20
opportunities for localized corridors of heavy rainfall with 1-2=20
inch per hour rain rates, and resulting flash flooding. The precise
placement remains somewhat uncertain, so the Marginal Risk remains
relatively broad to account for a variety of scenarios. In
particular, the risk area was fanned out a bit more to the north
and west than deterministic WPC QPF would imply, because of the
relatively slow pace of the ongoing convection and the very common
northeast placement bias in this sort of mesoscale setup respectively.

Lamers


Day 2
Valid 12Z Sat Apr 25 2026 - 12Z Sun Apr 26 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE ARKLATEX
REGION INTO EASTERN OKLAHOMA AND SOUTHEAST KANSAS...

It seems likely that scattered thunderstorms will develop on
Saturday afternoon in a corridor of strong instability across the
Southern Plains. However, there remains considerable uncertainty as
to the position of surface boundaries and the northward extent of
the strongest instability. Despite model guidance depicting a
variety of mesoscale scenarios, most models do show organized
convective clusters pushing southeast along the 1000-500mb
thickness gradient into the evening and overnight hours. This
motion could allow for some training and areas of locally heavy
rainfall; the strong instability and PWs of 1.2 to 1.5 inches would
support 1-2 inch per hour rain rates. If those rain rates can be
sustained for a couple hours, localized flash flooding would be
possible. For now the Marginal Risk was maintained as model
guidance does not really show any extended duration of training at
this point, and there is not enough model agreement to identify a
preferred corridor for heavy rainfall.

Lamers


Day 3
Valid 12Z Sun Apr 26 2026 - 12Z Mon Apr 27 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL IN THE CENTRAL
PLAINS AND OZARKS...

Strong cyclogenesis in the central Plains on Sunday will facilitate
significant northward moisture transport and a more expansive area
of thunderstorm activity stretching from the Dakotas south toward
Arkansas. The stronger signal for heavy rain exists further north
where stronger synoptic forcing and mid-upper level height falls
will be focused. However, instability is expected to be more
limited in those areas. Nevertheless, the combination of moderate
instability with PWs exceeding 1 inch and potential for more
persistence of rain and thunderstorms could yield localized flash
flooding. Further south, stronger instability could support higher
rain rates, but weaker forcing overall may keep convection
scattered and reduce opportunities for training and focused
corridors of heavy rainfall. Some portions of Kansas, Missouri,
Oklahoma, and Arkansas will likely have experienced substantial
rainfall in the preceding several days, and so may be more prone to
runoff issues if organized thunderstorms are more persistent. The
expected tradeoffs between convective coverage and available
instability, with respect to the overall flash flood threat, only
merit a broad Marginal Risk at this time.

Lamers
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 270750
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
350 AM EDT Mon Apr 27 2026

Day 1
Valid 12Z Mon Apr 27 2026 - 12Z Tue Apr 28 2026

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

Multiple rounds of convection are expected today ahead of a cold
front extending from an anomalously deep spring low. Significant
northward moisture transport will result in a plume of PWs above 1
inch as far north as Lake Superior, and above 1.5 inches as far
north as Chicago. Along the entire length of the cold front, these
values will generally approach the 99th percentile for late April
and, combined with moderate to strong instability, should support
hourly rain rates in the 1 to 2 inch range. A limiting factor for
flash flooding will be the dominant convective mode -- very likely
to be relatively narrow squall lines, forced by a steadily
advancing cold front, that will limit the overall duration of the
heavy rain rates.

However, an area from northern and central Missouri, into much of
Illinois and Indiana, will have a greater potential for training
convection. This will be due to a significant upstream complex of
thunderstorms over northeast Kansas as of 07Z, which should shift
east over the remainder of the morning. The orientation of the
convective line is closer to parallel with the deep layer shear
vector, which will favor training over northern Missouri at the
start of the period. Eventually, this activity may produce an
outflow boundary oriented in a west-east fashion that would focus
subsequent convective development in a more favorable configuration
for additional training. The broad Slight Risk was maintained and
adjusted to better fit the latest guidance where probabilities of 1
inch per hour rain rates are highest.

Further south, a Marginal Risk was extended from Arkansas and
Tennessee southwest into central Texas to account for a conditional
threat of localized heavy rainfall and flash flooding. The
environment in these areas will be characterized by strong
instability (CAPE in excess of 3000 j/kg) and abundant deep
moisture (PW between 1.5 and 1.8 inches). The QPF signal in
guidance is inconsistent, but enough to indicate a threat for
isolated to scattered thunderstorms, primarily in the afternoon and
evening. The combination of the aforementioned instability with
strong deep layer shear could lead to a few slow-moving
supercells, which has been a theme in recent days. It is a classic
conditional threat -- while much of this region further south along
the front could remain dry, any storms that become organized and
rooted in the very unstable boundary layer could produce localized
very heavy rainfall.

Lamers


Day 2
Valid 12Z Tue Apr 28 2026 - 12Z Wed Apr 29 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM THE ARKLATEX
INTO THE MID SOUTH...

A favorable environment will exist for numerous organized
thunderstorms over the southern U.S. on Tuesday, with a broad warm
sector containing very strong instability (CAPE over 3000 j/kg),
deep moisture (PW climbing into the 1.6 to 2.0 inch range), and
strong deep layer shear (0-6km bulk shear 40-60 knots). In that
sort of environment, rain rates should reach 2 inches per hour. The
open question is what sort of mesoscale boundaries may exist to
focus convective development, and whether or not some of these will
be oriented in a west-east fashion (parallel to the bulk shear
vectors). Any prominent boundaries that are favorably oriented
could easily focus a corridor of significant rainfall and flash
flooding in this sort of environment. However, an equally plausible
scenario would be more scattered clusters and lines of
thunderstorms that can produce localized heavy rainfall and flash
flooding, but fail to focus the convection in a way that leads to
more significant totals. For now, it seems reasonable to maintain
the broad Slight Risk and wait for greater confidence in the
mesoscale details.

Lamers


Day 3
Valid 12Z Wed Apr 29 2026 - 12Z Thu Apr 30 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM CENTRAL AND
SOUTHEAST TEXAS TO THE CENTRAL GULF COAST...

The threat of excessive rainfall and flash flooding seems to be
increasing in the most recent set of model guidance, due to a
continuation of strong instability and the arrival of a plume of
unusual amounts of mid-level moisture. Backward trajectory
analysis indicates that moisture around 3km above the surface
originated in the tropical central Pacific, advected into the
southern U.S. by an anomalously strong subtropical jet (300mb winds
around 60+ knots) extending about 6000 mi. from the Marshall
Islands, to just south of Hawaii, all the way to Texas. This should
push PW values over the whole region above 1.7 inches, and above 2
inches in portions of Texas, which is quite unusual. For instance,
a 2+ inch PW has only been observed on an upper air sounding at
Corpus Christi 3 times prior to May 1st (36 year period of record;
since 1990). Although model QPF is not exceptionally high at this
point, that may largely be a function of a lack of high-res
guidance from convection-allowing models. The environment (when
also considering strong bulk shear to around 50 knots) would favor
organized thunderstorms with very high rain rates, potentially in
excess of 2 inches per hour. Given that the previous outlook had
probabilities below 5 percent, the main change with this update is
to introduce a Marginal Risk, but a further upgrade may be
required, especially across parts of Texas.

Lamers
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 280808
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
408 AM EDT Tue Apr 28 2026

Day 1
Valid 12Z Tue Apr 28 2026 - 12Z Wed Apr 29 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM THE ARKLATEX
REGION INTO THE MID SOUTH...

A favorable environment will exist for numerous organized
thunderstorms over the southern U.S. today and tonight. Outflow
from steadily advancing squall lines over the Tennessee Valley
should provide a more distinct focus for renewed convective
development over the forecast period. The boundary is likely to be
oriented west-east, essentially parallel to 40-50 knot bulk shear
vectors. Although the air mass north of the boundary may modify
with time, it should still provide low-level convergence and a
contrast in instability. South of the boundary, the warm sector
will have very strong instability (CAPE over 3000 j/kg) and deep
moisture (PW approaching 2 inches; above the 99th percentile for
late April). This parameter space is very supportive of high rain
rates, potentially in excess of 2 inches per hour in the most
intense and organized thunderstorms.

If anything, recent hi-res model runs (06Z HRRR, 00Z RRFS in
particular) have focused the heavy rainfall signal even more into a
corridor approximately 100 miles wide, with 2-4 inch totals and
localized maxima even higher. This is consistent with the expected
pattern described above, with repeated rounds of thunderstorms
along a distinct mesoscale boundary. The main change with this
outlook was to narrow the Slight Risk a bit, especially by trimming
from the stable (northern) periphery well into the stable side of
the mesoscale boundary. It could potentially be focused a bit more,
and that will be a consideration later today. A mitigating factor
for flash flood impacts could be the severe to extreme drought
conditions in place across much of the Slight Risk area. With rain
rates potentially in excess of 2 inches per hour, and heavy rain
sustained for several hours in some cases, drought conditions may
not necessarily prevent impacts but could lead to more isolated
instances of flash flooding. This is still consistent with the
Slight Risk definition. Flash flood guidance factors in current
ground and streamflow conditions, and HREF and REFS probabilities
still show about a 15-30 percent chance of exceeding FFG despite
the overall dry antecedent setup.

Lamers


Day 2
Valid 12Z Wed Apr 29 2026 - 12Z Thu Apr 30 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM CENTRAL AND
SOUTHEAST TEXAS TO THE CENTRAL GULF COAST...

The outlook for Day 2 has remained mostly unchanged, with a
Marginal Risk in a corridor from Texas through Alabama along the
western and central Gulf Coast. A threat of excessive rainfall and
flash flooding is expected, due to a continuation of strong
instability, and the arrival of a plume of unusual amounts of mid-
level moisture. Backward trajectory analysis indicates moisture
around 3km above the surface can be traced along an anomalously
strong subtropical jet extending back into the tropical central
Pacific Ocean. This should push PW values over the risk area above
1.7 inches, and above 2 inches in portions of Texas, which is quite
unusual for April. Given this, it's possible an upgrade to Slight
Risk may be needed in future outlook updates. However, hi-res
guidance is just coming into view. While the extended HRRR and RRFS
do both show rain rates in this environment reaching (and even
exceeding, in some cases) 2 inches per hour, confidence is not high
on placement of greater concentrations of convection. Additionally,
there doesn't seem to be much signal for backbuilding and training,
except perhaps via cell mergers, which could lead to more limited
duration of heavy rain. Therefore, the risk level was held at
Marginal for now for the entire region.

Lamers


Day 3
Valid 12Z Thu Apr 30 2026 - 12Z Fri May 01 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN CENTRAL TEXAS...

Increasing mid-upper level height falls over New Mexico and Texas,
due to a strong shortwave pushing through northern Mexico, should
lead to a low-level mass field response with increasing south to
southeast inflow across southern and central Texas. That will also
lead to a gradual uptick in low-level convergence between the
developing low-level jet, and an easterly cool conveyor belt to
the north, in a more stable region from Oklahoma into northwest
Texas. The result should be more numerous thunderstorms over the
course of the Day 3 period, particularly by Thursday Night. Deep
moisture will remain firmly in place, although the instability
should shift to a narrower CAPE profile with lower equilibrium
levels. That trend, in combination with PWs of 1.5 to 1.8 inches,
should support increasingly efficient, warm rain processes in
convective bands.

Furthermore, some training of the lower-topped convective bands may
occur. With stronger instability over South Texas, the Rio Grande
Valley, and far northeast Mexico, and steadily increasing forcing
from the approaching wave upstream, persistent new convective
growth upstream of convective bands is plausible.

Putting all these factors together, a Slight Risk was introduced
over Central Texas. This was placed where drought conditions either
do not exist or are much lower on the scale; that also happens to
be where some ensemble QPF signal is strongest. It's possible the
Slight Risk may trend southeast with time as AI guidance is
positioned on the southeast flank of the guidance envelope, and
would seem to be a logical corrective to the usual bias of QPF
maxima placed too far in the direction of a stable air mass,
especially with 2-3 days of lead time.

Lamers
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 010838
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
438 AM EDT Fri May 1 2026

Day 1
Valid 12Z Fri May 01 2026 - 12Z Sat May 02 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN CENTRAL AND
SOUTHEAST TEXAS EASTWARD ALONG THE CENTRAL GULF COAST...

Once again...minor reshaping of the Marginal and Slight Risk areas
were made to reflect small adjustments made in the WPC
deterministic QPF and the suite of 01/00Z global and CAM guidance. The
axis of the heaviest rainfall still forecast to span from eastern
Texas to eastern Louisiana and southern Mississippi where the best
moisture convergence and instability will be present. Recent rains
across the western an central Gulf states have increased soil
saturation, lessening the amount of additional rainfall required
for areas of flash flooding. Hourly rates of 1 to 3 inches/hr to
streak from eastern Texas to eastern Louisiana.

The overall evolution aloft coupled with a broad axis of
formidable moisture anomalies and instability should lead to an
axis of heavy rainfall across the Southern Plains from Texas over
through the Lower Mississippi Valley today into early Saturday
morning. A quasi-stationary front will orient itself across south-
central TX down to around the Gulf coast as a wave of low pressure
rides along the boundary. With precipitable water values forecast
to be 1.7 inches to 2.1 inches (in the 95th percentile or higher
for this time of year)...efficient warm rain processes can result
in torrential downpours with resulting flash flooding especially in
light of the upper divergence tied to the mid- and upper level
wave making its way through the southern Great Basin early this
morning. Thus there is little overall change to the forecast
reasoning for a high-end Slight risk area from parts of Texas into
Louisiana embedded within the broader Slight Risk area.

Farther east...the Slight risk area tapers off into a Marginal Risk
area where rainfall rates and amounts still have the potential to
result in flash flooding but where ingredients are not as well
aligned. The question in dry/drought areas always comes down to
rates and resulting amounts (whether it is from training or repeat
rounds). Thinking here rates may not be enough alone (with PW's
generally < 1.75-ish) but some potential for training prior to
frontal passage. The 01/00Z HREF neighborhood probs for 1-hr amts
at 1 in and 2 in thresholds focused generally along the LA/MS coast
(admittedly sub SLGT). The RRFS..which has a tendency to be
overconfident with probs and overly expansive...seemed to show its
bias on its 30/18Z run but focused pretty much along the same axis.
There remained some question on the latitude of the
axis...considering the latest UFVS verified machine learning
guidance focused a bit north of the HREF/RRFS axis closer to the
support offered by an upper jet streak.

Bann


Day 2
Valid 12Z Sat May 02 2026 - 12Z Sun May 03 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHEAST U.S....

A progressive upper trough is expected to help focus and sustain
showers and thunderstorms across portions of the Southeast United
States on Saturday into the early morning hours of Sunday. More importantly...the trough should result in any convection moving
with minimal risk of back-building or training. The setup promotes
a relatively favorable environment suitable for heavy rainfall
with the stronger cell cores capable of producing rainfall rates
between 1-2"/hr in a region where Flash Flood Guidance values
remain high. There was enough of a signal for the possibility of
some urban flooding to warrant keeping a previously-issued Marginal
Risk in place with minimal amount of changes needed.

Bann


Day 3
Valid 12Z Sun May 03 2026 - 12Z Mon May 04 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THEm SOUTHEAST FLORIDA PENINSULA ON SUNDAY...

A cold front associated with an area of low moving northeastward
off the eastern US seaboard will be draped across the central
portion of the Florida peninsula on Sunday...with the front
separating an airmass with precipitable water values at or
somewhat less than 0.5 inches in the panhandle and adjacent
portions of the peninsula to values in the 1.75 inch to 2.00 inch
over the southern half of the peninsula for much of Sunday and
Sunday evening. Mid- and upper-level shortwave energy embedded
within fast flow aloft will help focus and sustain thunderstorms
that could produce 1.5 to 2.5 inch per hour along and south of the
boundary. There remained enough of a signal for the potential of
some urban flooding across the larger urban areas so opted to keep
with the Marginal Risk area due to the high flash flood guidance.
Even if the QPF remains similar in future cycles...where/how much
rain falls in Days 1 and 2 will affect the flash flood guidance as
Day 3 makes its way towards becoming a Day 1 outlook.
Regardless...downpours and localized multiple-inch rainfall amounts
in the major cities is more likely to have flood- related problems
in either scenario.

Bann
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 030825
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
425 AM EDT Sun May 3 2026

Day 1
Valid 12Z Sun May 03 2026 - 12Z Mon May 04 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE SOUTHEAST FLORIDA PENINSULA...

Just enough of a signal in the 03/00Z CAMS to maintain the Marginal
Risk area. The focus will be over the urban southeast coast as a
front advances into a region of deeper moisture and where CAPE
tends to be under 1000 J per kg. The 03/00Z HREF does depict a
low-end neighborhood probability of FFGs being exceeded over the
southern tip of the Florida peninsula in the 03/21Z to 04/00Z
period but the stronger signals in the guidance is for heavier
rainfall to be hugging the coast or remaining just off-shore. It
was noted that over the past couple of days...numerical models have
been cutting back the amount of moisture in the lowest layers which

Bann


Day 2
Valid 12Z Mon May 04 2026 - 12Z Tue May 05 2026

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

Bann


Day 3
Valid 12Z Tue May 05 2026 - 12Z Wed May 06 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE MID MISSISSIPPI VALLEY INTO THE OHIO VALLEY...

Deep layer southwesterly flow leading into the start of the period
will be drawing moisture into parts of the Plains and then
downstream toward the Great Lakes and the Ohio Valley. As a trough
amplifies over the central part of North America and a jet streak
forms over the Southwest US and approaches the Plains...the chance
for showers and thunderstorms increases along and ahead of a
develops surface front. With precipitable water values of 1.75 to
1.9 inches embedded within a broader 1.5 to 1.75 area...which was
pushing two standardized anomalies greater than climatology for
this time of year--locally heavy rainfall and the associated risk
of localized flooding from late Tuesday afternoon into early
Wednesday is possible.

Bann
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 040826
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
426 AM EDT Mon May 4 2026

Day 1
Valid 12Z Mon May 04 2026 - 12Z Tue May 05 2026

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

Bann


Day 2
Valid 12Z Tue May 05 2026 - 12Z Wed May 06 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE MID MISSISSIPPI VALLEY INTO THE OHIO VALLEY...

Deep layer southwesterly flow leading into the start of the period
will be drawing moisture into parts of the Plains and then=20
downstream toward the Great Lakes and the Ohio Valley. That large=20
scale picture has changed little but subtle run to run difference=20
in the global models and convective allowing models continues to=20
result in minor adjustments to the ERO. A mid- and upper-level=20
trough will be amplifying over the central part of North America=20
and a jet streak forms over the Southwest US and approaches the=20
Plains...the chance for showers and thunderstorms increases along=20
and ahead of a develops surface front. With precipitable water=20
values of 1.75 to 1.9 inches embedded within a broader where=20
precipitable water values of 1.5 to 1.75 are going to be more=20
common...areal average rainfall is expected to be on the order of 1
to 1.25 inches. In general this will be beneficial rain. However=20
there may be isolated areas where rain rates lead to local flash=20
flooding. There was spread between model members with the ARW core
favoring a western solution while models with an NMM core favored
areas farther east. Given the synoptic pattern and with the support
of the global models...the ERO was kept in general along and east
of the Mississippi River.

Bann


Day 3
Valid 12Z Wed May 06 2026 - 12Z Thu May 07 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE INTERIOR SOUTHEAST UNITED STATES...

Maintained a Slight Risk of excessive rainfall introduced by the
WPC Medium Range desk as shortwave energy drops out of Canada and
across much of the central and eastern United States. The coverage
and rainfall intensity should be increasing on Wednesday as the
best dynamics and the best Gulf moisture coverage with a frontal
boundary over the interior portion of the Southeast US.=20
Deterministic QPF tends to cluster in the 1.5 to 3 inch amounts=20
across part of the Tennessee Valley into the southern Appalachians
from Wednesday into early Thursday due to the presence of surface=20
dewpoints close to 70 degrees getting drawn northward from the=20
Gulf. Whether or not the convection evolves into line will affect=20
the amount of rainfall and any associated risk of flash flooding.

Bann
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 050827
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
427 AM EDT Tue May 5 2026

Day 1
Valid 12Z Tue May 05 2026 - 12Z Wed May 06 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE MID MISSISSIPPI VALLEY INTO THE OHIO VALLEY...

Deep layer southwesterly flow had drawn Gulf moisture into parts
of the Plains and then downstream toward the Great Lakes and the
Ohio Valley. The resulting showers and thunderstorms today will be
able to tap into an atmosphere that generally has 1.5 inch
precipitable water or greater extending as far north as Ohio by the
overnight hours. The southeastward adjustment of the Marginal Risk
area still looks good and spans the placement of the 2 inch
contour shown by a handful of ARW-core and NMM-core ensemble
members. So few changes were needed and were not made due to a
fundamental shift in forecast reasoning.

Bann


Day 2
Valid 12Z Wed May 06 2026 - 12Z Thu May 07 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE INTERIOR SOUTHEAST UNITED STATES...

Maintained the slight southward shift of the previously issued Slight
Risk area introduced a couple of days ago. The coverage and
rainfall intensity should be increasing on Wednesday as a large
scale trough over the northern Plains continues to amplify and
result in a 140 kt to 160 kt upper level jet over the Tennessee
Valley during the latter part of the period. The resulting upper
divergence, steepening mid-level lapse rates and increasing
moisture and instability should result in convection capable of
producing heavy rainfall rates and embedded areas of rainfall
amounts of 3 to 5 inches as suggested by the latest run of the
RRFS. There is a fairly wide spread in the north/south placement of
that heavier axis. As a result...the Slight area was expanded
somewhat and tended to cover the greatest overlap of higher QPF and
exceedance probabilities. Thinking is that there are some
probabilities supportive of a higher-end slight risk embedded
within the broader Slight. The continued amplification of the upper
trough should keep the convection moving southward with time
during the overnight hours.

Bann


Day 3
Valid 12Z Thu May 07 2026 - 12Z Fri May 08 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE GULF COAST REGION TO THE SOUTHEASTERN UNITED STATES...

Showers and thunderstorms along and ahead of a surface cold front
will be lingering into Thursday from parts of the Gulf coast region northeastward into parts of Georgia and South Carolina. At this point...rainfall rates look to be decreasing as the better upper
level dynamics pull off to the northeast and low level flow becomes
directed along...rather than normal...to the front. Maintained a
Marginal Risk area where there could be overlap with areas somewhat
higher soil moisture content from recent rainfall. Overall the
rainfall looks to be more beneficial than not.

Bann
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 101800
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
200 PM EDT Sun May 10 2026

Day 1
Valid 16Z Sun May 10 2026 - 12Z Mon May 11 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
CENTRAL AND NORTH TEXAS...

...16Z Update...

The Slight Risk area was expanded a bit with this update, mostly
towards the south but also to include the rest of the DFW
Metroplex. Clusters of storms are expected to develop this
afternoon, likely as a continuation of the showers and storms
ongoing currently over Oklahoma, but developing further south into
Texas. Much of the convective activity is expected to congeal south
and west of the Metroplex, but urban concerns and some expected
development over the Metroplex still heighten the flash flooding
risk into the lower-end Slight category. Meanwhile, while
convection will be more numerous and strong further south and west,
less urban development may help to mitigate the flash flooding
threat a bit. By late evening, around 03Z/10pm CDT or so, the
convection is expected to have organized into a mostly single line
of storms that will progressively shift southeast towards the Gulf.
This should greatly mitigate the flash flooding threat by that
point and beyond. Thus, the flash flooding threat is greatest in
the late afternoon and evening while the storms are still
organizing and therefore have more chaotic and slow forward motions.

Wegman

...Previous Discussion...

The overall forecast philosophy for the new Day 1 period remains
largely consistent with the previous thinking, though an upgrade to
a Slight Risk has been introduced for portions of Central and
North Texas. While some uncertainty remains regarding the exact
evolution of the convective elements, a growing signal for higher-
end rainfall totals is becoming evident in the latest guidance.

Totals of 2-4 inches are increasingly likely across portions of
Central and North Texas by the late afternoon and evening,
supported by a moist, unstable airmass and strong ascent. Deepening
moisture is expected to pool along a composite surface boundary,
with PWs climbing to around 1.5 inches near the intersection of the
cold front and dryline. This moisture is expected to interact with
strong low level convergence and increasing upper level divergence
as a shortwave trough moves east, generating numerous storms
capable of producing heavy rainfall rates.

Further raising the concern for heavy amounts and potential flash
flooding will be cell training. Storms developing along the
boundary and ahead of the approaching wave may track over some
areas repeatedly, leading to localized excessive totals. Both the
HREF and RRFS indicate the potential for this setup, showing their
highest probabilities for QPF exceeding 2 inches extending from
parts of Central into North Texas, including southern sections of
the DFW Metro. Therefore, the Slight Risk was introduced to reflect
increasing confidence for scattered flash floods within this area.

Elsewhere, the Marginal Risk was expanded a bit, but remains
centered across much of the same region, reflecting the potential
for convective storms and heavy rainfall rates, though with less
organization or lower confidence in the potential for heavy
accumulations in comparison to the upgraded Slight Risk area.

Pereira


Day 2
Valid 12Z Mon May 11 2026 - 12Z Tue May 12 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR THE CENTRAL
GULF COAST...

...18Z Update...

A Marginal Risk of excessive rainfall was introduced for the
central Gulf Coast with this update. A strong cold front pushing
south out of the interior U.S. will interact with still sufficient
Gulf moisture (PWATs between 1.5 and 1.75 inches) along the coast
to force a renewed round of convection ahead of the front, which
may also interact with the sea breeze. Corfidi vectors suggest
storm movement will be fast towards the east, so backbuilding
potential appears low. However, this area was hard-hit with heavy
rain totaling over 3 inches in several areas of southeast
Louisiana, with totals up to 2 inches across much of the rest of
the Marginal Risk area just yesterday. Thus, while the area will be
recovering today through tomorrow morning, expect that any heavy
rainfall of meaningful duration may still lead to an instance of
flash flooding or 2, especially in the urban areas within the
Marginal Risk.

Wegman


Day 3
Valid 12Z Tue May 12 2026 - 12Z Wed May 13 2026

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

Wegman
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 110808
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
408 AM EDT Mon May 11 2026

Day 1
Valid 12Z Mon May 11 2026 - 12Z Tue May 12 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR THE CENTRAL
GULF COAST...

Renewed convection expected along the Gulf coast as a strong cold
front pushes south into the Gulf. Sea breeze and pooling PW values
of 1.5 to 2.0 inches will help enhance rainfall along the central
Gulf Coast. Recent rainfall has increased soil saturation for
parts of the region which in turn reduces the amounts needed for
isolated instances of flash flooding. The latest guidance has areal
averages of 1 to 3 inches with very local maximums of 4+ inches.
The environment will be conducive for progressive storm motion
which may limit the threat for flooding problems, however isolated
flash flooding with be possible especially over sensitive soils. A
Marginal Risk remains in effect from eastern Texas to the Florida
Panhandle.

Campbell


Day 2
Valid 12Z Tue May 12 2026 - 12Z Wed May 13 2026

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

Campbell


Day 3
Valid 12Z Wed May 13 2026 - 12Z Thu May 14 2026

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

Campbell
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 120811
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
411 AM EDT Tue May 12 2026

Day 1
Valid 12Z Tue May 12 2026 - 12Z Wed May 13 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR ALONG THE
I-95 CORRIDOR IN FLORIDA...

Heavy rainfall possible along the eastern coast of Florida during
this period as a cold front advances southward through the state.
Onshore flow along with pooled PW values in excess of 1.75 inches
will help fuel enhanced rainfall initially. Diurnal seabreeze=20
effects will interact further with the cold front, with a=20
convergence axis expected along the east coast of Florida.
HREF neighborhood probabilities suggest a high likelihood (over=20
90%) of QPF exceeding 3 inches, and a moderate chance (around=20
60-80%) over the urban center of Jacksonville. Due to ongoing=20
drought conditions, most of the rainfall will be beneficial which=20
will result in a low-end marginal threat for much of the eastern=20
coastline of Florida.

Campbell


Day 2
Valid 12Z Thu May 14 2026 - 12Z Fri May 15 2026

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

Campbell


Day 3
Valid 12Z Thu May 14 2026 - 12Z Fri May 15 2026

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

Campbell
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 190745
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
345 AM EDT Tue May 19 2026

Day 1
Valid 12Z Tue May 19 2026 - 12Z Wed May 20 2026

...THERE ARE SLIGHT RISKS FOR EXCESSIVE RAINFALL FOR PORTIONS OF=20
TEXAS AS WELL AS FOR SOUTHERN ILLINOIS AND INDIANA...

...Texas...

A line of intense showers and thunderstorms currently expanding=20
south across northern and western Oklahoma will continue south and
east through the early morning into northeast Texas. With peak
solar heating around midday, the line of storms will encounter an
increasingly unstable, and increasingly moist air mass situated
across much of Texas. Guidance suggests that several lines of
storms will develop in north Texas through the early afternoon.
Cold pools and lift ahead of the lines should allow individual
cells to develop out ahead of the lines, which will locally
increase the duration of heavy rains in those areas hit by first
the cells, and then the line shortly thereafter. This could cause
local flash flooding, especially should that occur over the
Metroplex or other urban areas in north Texas. By mid to late
afternoon, upper level energy may support areas of convection
across central and south Texas that will be separate from any lines
to the north. Mergers with the lines as they press south across the
state and any individual cell mergers within the clusters of storms
may also pose a localized flash flooding threat. By evening, the
storms will continue pushing into south Texas, potentially
impacting the San Antonio and Houston metros before they push into
the Gulf and deep south Texas through the predawn hours.

Overall the above-described scenario should keep flash flooding
instances mostly to localized, widely scattered occasions. However,
since the storms will cover much of the state, it's probable that
in flood prone areas, the flash flooding threat could be greater. Unsurprisingly with so many clusters of storms expected, the CAMs
are not having a great handle on them, so the Slight was expanded
to cover the Texas Triangle. Despite the antecedent dry soil
conditions over most of the state, PWATs will likely exceed 2
inches along the Gulf Coast for when the storms reach there
tonight. Thus, any and all storms will be capable of heavy rainfall
rates that could cause flash flooding.

...Southern Illinois and Indiana...

After rounds of showers and storms caused flash flooding in
portions of Illinois and Indiana yesterday, the soils in the area
are generally saturated due to widespread multiple-inch totals from yesterday/Monday. Much of the day today will be dry. Towards=20
evening however, renewed rounds of showers and thunderstorms will=20
develop with the approach of a strong cold front, significant=20
moisture and instability advection ahead of the front, and upper=20
level disturbances helping add to the overall environmental=20
forcing. Thus, overnight, expect multiple rounds of training
showers and thunderstorms tracking up the Ohio River Valley. With a
robust LLJ supporting the storms, they should have no trouble
maintaining their organization despite the lack of solar heating.
Since the soils are fully saturated, most, if not all the rainfall
will convert to runoff. Thus, the inherited Slight Risk was
expanded southwest to include much of southern Illinois with this
update.

Wegman


Day 2
Valid 12Z Wed May 20 2026 - 12Z Thu May 21 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE EDWARDS
PLATEAU REGION OF SOUTHWEST TEXAS...

A developing low level jet of deep Gulf moisture will advect
northwestward up the Rio Grande in south and southwest Texas in
response to height falls and an approaching shortwave moving
towards that area from Mexico. Numerous showers and thunderstorms
will develop late afternoon across the Edwards Plateau as a dry
line pushes east from the Big Bend area. The storms feeding off
PWATs of 1-1.5 inches, which is 2-2.5 sigma above normal for this
time of year in that part of the country are expected to become
plenty capable of producing heavy rain in an otherwise dry part of
the country. More susceptibility and plenty of topography in the
area will reduce the amount of rainfall needed to develop flash
flooding concerns. A general 1.5 to 2 inches of rain are expected
in the Edwards Plateau along the Rio Grande, likely falling in a
1-3 hour period as the storms track eastward down the plateau.
Thus, a higher-end Slight is in effect from Eagle Pass north and
west. As the storms move off the Rio Grande into central Texas,
generally towards San Antonio, they should weaken with time as they
separate from the dry line and the upper level shortwave rapidly
races away by the predawn hours Thursday. This should diminish the
flash flooding threat further east for this period.

Another area of more concentrated shower and thunderstorm activity
will impact the lower Mississippi Valley along the
Louisiana/Mississippi border Wednesday afternoon and evening. Due
to high FFGs and a lack of agreement in the guidance as to the
convective evolution, the area remains in a Marginal for now, but
should heavy rain producing storms move over an urban area such as
Baton Rouge, then flash flooding could occur. This area will need
to be monitored for a Slight Risk upgrade with future updates.

Wegman


Day 3
Valid 12Z Thu May 21 2026 - 12Z Fri May 22 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF THE
SOUTHERN PLAINS THROUGH THE OZARKS...

Numerous areas of showers and thunderstorms will impact the Slight
Risk area on Thursday through Thursday night. An ensemble of
guidance that covers the Day 3/Thursday period generally agree that
Thursday morning, the strongest storms will be across coastal Texas
through central Texas. These storms will track northeastward and
grow upscale as the impact areas from northern Louisiana, northeast
Texas, and Oklahoma. Thursday evening, a new round of storms
impacts south Texas as the rest of the storms push northeast into
Arkansas, northeast Oklahoma, and into Kansas, which then continue
northeast up the mid-Mississippi River Valley and a separate area
of storms impacts the Kansas City area. Despite this broad
evolution, there is very little confidence on how the storms will
behave/merge or track. Thus, the Slight covers likely more
saturated soils after rainfall expected in many of these areas on
Days 1 and 2. There will be no shortage of moisture and instability
across the Slight Risk area, especially the southern half, so it's
likely any limiting factor will be a generally progressive forward
speed to the storms, and cold pool interactions.

It's likely that with future updates, CAMs guidance should help
narrow down where the greatest threats for storms will be on
Thursday. This should allow the Slight to shrink a bit with better
confidence, though much of the region should see at least some rainfall.

Wegman
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 200800
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Wed May 20 2026

Day 1
Valid 12Z Wed May 20 2026 - 12Z Thu May 21 2026

...THERE ARE SLIGHT RISKS FOR EXCESSIVE RAINFALL OVER PORTIONS OF
SOUTHWEST TEXAS, AS WELL AS FOR EASTERN LOUISIANA INTO SOUTHERN MISSISSIPPI...

...Southwest Texas...

Numerous showers and thunderstorms are expected to develop over
much of southwest Texas, generally along the Rio Grande from south
Texas through the Edwards Plateau this afternoon into tonight.
Convection is likely to initiate over the mountains of Mexico and
along the dry line north and northeast of the Big Bend Region this
afternoon. Meanwhile a surge of deep Gulf moisture, characterized
by PWATs nearing 2 inches, will advect up the Rio Grande Valley on
a 15-25 kt southeast wind from the Gulf. Where the dry line and
this surge of moisture meet is where the heaviest and most
persistent showers and storms capable of producing heavy rain will
occur. This appears most likely in the portion of the Edwards
Plateau near Del Rio. A higher-end Slight remains in effect for
this area where the greatest potential of seeing 3 inches or more
of rain areally, with locally higher amounts exists. HREF
neighborhood probabilities peak over 30% of seeing 5 inches of rain
in this area. Given the steep topography, rocky soils, and
climatologically dry nature of the area, flash flooding appears
likely, especially where the storms are most persistent.

During the evening, the storms are likely to separate both from the
mountains of Mexico as well as the dry line. They will follow
generally parallel to the Rio Grande towards the southeast,
following the influx of deep Gulf moisture and instability. Due to
recent heavy rainfall from Laredo east through Corpus Christi, the
soils here are more saturated, and therefore should be more likely
to convert more rainfall to runoff, despite the storms by that
point likely being quite progressive. Thus, the Slight extends
south to around Laredo.

...Eastern Louisiana into Southern Mississippi...

In coordination with LIX/Slidell, LA and JAN/Jackson, MS forecast
offices, a small Slight Risk upgrade was introduced with this
update for eastern Louisiana into southern Mississippi. A stalling
out cold front over central Louisiana will provide the greatest
forcing for storms as it tries to progress eastward. Deep Gulf
moisture and instability will ramp up ahead of the front with peak
heating. However, thunderstorms may still be in progress along the
coast from the current storms over Texas. New convective initiation
will occur along the front, likely just east of the Mississippi
River in Mississippi, and those storms will link up with other
clusters of storms further south and west over southwestern
Louisiana. Since the front will be slow-moving, and there will be a
steady southerly flow of Gulf moisture out ahead of it, the storms
will likely have some training elements to them. During peak
heating in the mid to late afternoon, the storms will progress into
Baton Rouge and New Orleans, adding an urban element to the flash
flooding threat. Given the proclivities for those urban areas to
flash flood during heavy rain events, the Slight Risk upgrade was
introduced. The storms will then progress north into southern
Mississippi, which while far less urban, still has somewhat wetter-
than-normal soils, which could also promote flash flooding in some areas.

Wegman


Day 2
Valid 12Z Thu May 21 2026 - 12Z Fri May 22 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
SOUTHERN PLAINS AND PINEY WOODS REGIONS...

...Southern Plains into the Piney Woods...

The dry line across western Texas and Oklahoma will make a big push
to the east through the Day 2/Thursday period. The former cold
front over eastern Texas will retreat as a warm front towards the
north and as renewed push of deep Gulf moisture advects northward
with the low level jet. Further, a deep positively tilted longwave
trough will eject into the Plains from the Rockies during this
period. The combination off all of these factors will result in a
large and widespread area of convection stretching from the Gulf
Coast of Texas north across eastern Oklahoma and Kansas, as far
north as Kansas City.

Starting from the south, the convection along the Texas Gulf coast
will be associated with the dry line pushing quickly east and
running into plentiful Gulf moisture ahead of it. Expect most of
the storms from Houston south and west to be fast movers with the
dry line. Most of these storms will impact coastal communities
Thursday morning. Further north, there will likely be convection
ongoing at the start of the period across north Texas (near the
Wichita Falls area) and into southwestern Oklahoma. These storms
will increase in coverage through the morning as they progress over
central Oklahoma. Meanwhile by afternoon, the storms will blossom
over northeast Texas and down into northern Louisiana. With
moisture continuing to advect north, expect numerous clusters of
storms over much of eastern Oklahoma, eventually moving into
western Arkansas in the early evening. These areas got pockets of
1-3 inches of rain yesterday, so the newly saturated soils across
western Arkansas should support widely scattered instances of flash
flooding as multiple rounds of storms move through, and they
backbuild south and west. Due to the southerly flow of Gulf
moisture, some convection should also progress northward into
eastern Kansas and western Missouri through the evening. By this
far north instability will be lacking, so not expecting
particularly heavy rain, but all of the stronger storms to the
south will have merged into a larger area of moderate rain into
Kansas and Missouri, which have also seen heavy rains lately,
supporting Slight Risk levels of flash flooding. The steady rain
there could continue well into Thursday night.

...Southern Appalachians...

The clash of a cool air mass behind a back door cold front over
Virginia and tropical Atlantic moisture across the Southeast
characterized by PWATs over 1.5 inches will support areas of
showers and storms across portions of southwest Virginia, western
North Carolina, and perhaps into far eastern Tennessee Thursday
afternoon into Thursday night. Training convection along the front
will be likely, especially along the Virginia/North Carolina border
area, where the topography of the southern Appalachians could
locally further enhance rainfall rates. Instability will be
marginal however due to extensive cloud cover over this area.
While the meteorology may support a bit more widespread flooding,
the hydrology will be strongly working against that. A long-term
drought over the area and extremely dry soils compared to
climatology will make much of the rain expected in this area
beneficial. However, due to training, plentiful moisture that will
support areas of heavy rainfall, and the topography, isolated
instances of flash flooding are probable. For now the area remains
in a Marginal Risk, but a Slight may need to be considered if
forecast rainfall amounts in this area increase appreciably over
the next day or so.

Wegman


Day 3
Valid 12Z Fri May 22 2026 - 12Z Sat May 23 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER THE LOWER TO
MID MISSISSIPPI VALLEY, OHIO VALLEY, AND PORTIONS OF THE SOUTHERN PLAINS...

As a longwave trough over the northern Plains pivots northeastward
through the period, a surface cold front tracking along with it
will likely slow its eastward progress along the Mississippi and
Ohio Valleys. Plentiful Gulf moisture ahead of the front will
support numerous areas of convection all throughout the Marginal
Risk area. With the greatest upper level forcing moving away from
the front, it will become an increasing struggle to organize the
convection in a way such that flooding becomes more likely. From
the Ohio Valley to the Mid-Atlantic, plentiful cloud cover and much
cooler temperatures will keep the instability near zero, precluding
any meaningful heavy rainfall in favor of a long-duration light to
moderate rainfall. The heaviest rains appear most likely into the
far southern Appalachians (northern AL/GA, western Carolinas, and
Tennessee). This is the area that appears most likely to have a
Slight Risk upgrade with future updates. Elsewhere, other MCSs may
impact the lower Missouri Valley, and along the Texas coast. Dry
line convection into Friday evening may impact a good amount of
Oklahoma, but once again the storms do not appear to be able to
organize to increase the flooding threat beyond the
isolated/Marginal category.

Wegman
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 210808
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
408 AM EDT Thu May 21 2026

Day 1
Valid 12Z Thu May 21 2026 - 12Z Fri May 22 2026

...THERE ARE SLIGHT RISKS FOR EXCESSIVE RAINFALL OVER PORTIONS OF
THE SOUTHERN PLAINS AS WELL AS FOR THE UPPER TEXAS COAST INTO
SOUTHWEST LOUISIANA...

...Southern Plains...

The combination of several ingredients coming together across
eastern Oklahoma and north Texas will be the driver for rounds of
training convection expected across the area. At the surface, the
nose of a low level jet will advance northward over Oklahoma,
spiking the PWATs over 1.5 inches this morning. Surface convergence
around a trough will support low level lift and thunderstorm
formation. An approaching upper level trough will increase the
divergence and lift in the upper levels. The result will be a
rather narrow corridor at first with mostly showers but some
thunderstorms by early afternoon, as the day is approaching peak
heating. Cold pools and speed convergence will focus the
convection, allowing training to become more likely as the storms
track northeastward. A secondary wave of thunderstorms will move
northward across north Texas, which will increase the areal
coverage of convection into the early evening hours. The
strengthening upper level shortwave driving this secondary wave
will become the primary forcing, allowing the complex of weakening
storms tonight to push northward and end the rainfall threat from
south to north. While the greatest flash flooding threat may be in
a rather narrow corridor from north Texas north and east through
Tulsa, sufficient Gulf moisture could still allow for flash
flooding in other areas as well.

The inherited Slight Risk was split with this update owing to
better CAMs agreement that from north Texas through Oklahoma will
be the best area for flash flooding risk, but less rainfall is
expected across east central Texas, between Houston and the
Metroplex, allowing for a downgrade to the risk in that area.

...Upper Texas Coast into Southwest Louisiana...

A large complex of storms currently over South Texas will push
northeast up the Texas Coast through the day today. The area will
have abundant Gulf moisture, instability, and some limited support
from the upper levels. Thus, any storms will be capable of very
heavy rainfall, but the time of the heavy rainfall in any one area
may be limited as the complex progresses northeastward. The area
was hit hard with very heavy rain yesterday, resulting in rainfall
totals over 5 inches near Freeport. As this second round of storms
moves through this morning, convergence into the storms, sea breeze
effects, and the saturated soils from yesterday's rains could
result in additional instances of flash flooding. The storms
continue into the Houston Metro around midday, introducing an urban
factor to the flash flooding threat. The storms then turn more
northward through the afternoon, ending the flash flooding threat
for the day along the coast. To summarize, the Slight Risk, albeit
a low- end one, remains in place mostly for the potential for very
heavy rains with PWATs approaching 2 inches and the favorably wet
soils overcoming the fast movement of the storms to result in flash flooding.

Wegman


Day 2
Valid 12Z Fri May 22 2026 - 12Z Sat May 23 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE EASTERN U.S....

The inherited Marginal Risk was left largely unchanged for many
areas with this update, save some trimming across both Oklahoma and
Missouri due to reduced signal for heavy rainfall in those areas.
Two areas in particular stand out as higher-end Marginal Risks,
where a Slight may be needed with future updates:

Across a portion of the Ohio Valley from northern Kentucky through
southern Ohio, efficient moisture advection will spike PWATs from
around 1.25 inches early in the day Friday to 1.75 inches by the
afternoon. With this added moisture, so too will instability
increase. Rain in the form of showers and thunderstorms following a
warm front, the same wave that will impact the Slight Risk areas on
D1/Thu will increase in coverage at peak heating Friday afternoon.
Mostly stratiform rain will lead the convection in the morning,
helping saturate the soils that in some areas of the Ohio Valley
remain nearly saturated from prior days' rains. Then during the
afternoon as instability and moisture rapidly increase and the
cloud cover and relative stability push north into northern Ohio
and Pennsylvania, areas of showers and storms will impact northern
Kentucky into southern Ohio. There remains considerable uncertainty
as to how much instability can develop given the short time frame
between the morning's stabilizing rains with the warm front and the
following convection. Further, there is uncertainty as to how the
storms will organize, with some training needed to produce anything
more than isolated instances of flash flooding. Thus, for now, the
Marginal was maintained, but is likely the higher of the two areas
for a potential Slight risk upgrade with future updates.

The other area of the large Marginal that is drawing additional
scrutiny is the area from north Georgia into the Carolinas. Here
moisture and instability will be plentiful, supporting clusters of heavy-rain-producing thunderstorms. Winds are generally
unidirectional which may support training. However, lack of forcing
with upper level ridging in place will act as a counter to allowing
the storms that form to organize. Thus, clusters of disorganized
convection will be unlikely to produce much in the way of flash
flooding. Further, much of this area is in severe drought, and
soils are extremely dry. Sandy soils would work against flooding as
well into the Piedmont, so that highly unfavorable hydrology should
also work to effectively keep any flooding threat in check.

Wegman


Day 3
Valid 12Z Sat May 23 2026 - 12Z Sun May 24 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF EASTERN
TEXAS AND WESTERN LOUISIANA...

Perhaps the most active day of the Days 1-3 period will be on
Saturday across eastern Texas into Louisiana. Plentiful moisture
and instability will be drawn north off the Gulf, spiking PWATs to
around 2 inches in some areas, and instability could peak over
4,000 J/kg right at convective initiation midday/early afternoon
Saturday. Lines of intense thunderstorms will develop in this
extremely favorable air mass during the afternoon. The storms will
generally track northeastward. However, as they move north,
additional clusters are likely to form as both moisture and
instability rapidly recover. In the upper levels a series of small
shortwaves, but nonetheless potent ones given the highly favorable
atmosphere will allow for new clusters of storms to form across
southeast Texas soon after the prior rounds move off to the north.

Once daytime heating wanes in the evening, it appears likely that
additional storms that form will predominantly move southeastward
towards the Gulf as they follow the instability. This could lead to
additional periods of heavy rainfall over many of the same areas
hit with heavy rains Saturday afternoon. Further, these storms
moving against the prevailing windflow could slow down the storm
movement, increasing both interaction potential between cells as
well as the duration of the heavy rainfall, this threat appears
particularly probable in the Houston metro area. With CAMs input
over the next day or so, a Moderate Risk may need to be considered
in and around the Houston metro, perhaps extending southwest along
the Texas coast with future updates.

Elsewhere, the Marginal across portions of the Northeast was
removed with this update as the warm front over the area will have
zero instability to work with, resulting in a long duration
stratiform rain. Some elevated convective elements may sneak their
way that far north, but the otherwise light rainfall should allow
any rain to soak into the soils with no flash flooding expected.
Conversely, a Marginal Risk was introduced for a portion of north
Georgia into the Carolinas. Following likely rain from storms on
D2/Friday, additional widespread storms are expected again Saturday
afternoon into the evening over many of the same areas. As on
Friday, forcing in this area will be very limited. The storms will
generally track east-southeast towards the coast, with enough
movement that interactions are generally unlikely to initiate
additional convection. Any lines of storms should align
perpendicular to the flow reducing the training risk. Finally,
despite any rains on Friday, the ongoing severe drought should
still greatly mitigate most of the flash flooding threat. Given the
plentiful moisture and instability the storms will have to work
with, they will still likely produce very heavy rain in their
cores, raising resultant flooding potential into the Marginal category.

Wegman
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 220909
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
509 AM EDT Fri May 22 2026

Day 1
Valid 12Z Fri May 22 2026 - 12Z Sat May 23 2026

...THERE IS A SLIGHT RISK FOR EXCESSIVE RAINFALL OVER THE UPPER
OHIO VALLEY AND THE SOUTHERN APPALACHIANS...

Shortwave energy embedded in broad southwesterly mid to upper
level flow from the western to central Gulf Coast, northeastward
through the TN/OH Valleys will persist through the upcoming day 1
period. These height falls/broad diffluent upper flow will enhance
uvvs in a large region of much above average PW values/anomalous
850-700 mb moisture flux, 2 to 2.5+/2-3+ standard deviations above
the mean respectively from the Gulf Coast northeastward into the
Ohio Valley. There is fairly good model consensus for the potential
for widespread moderate to heavy rainfall total in this anomalous
PW axis day 1. Simulated radars suggest cells will be fairly
progressive to the northeast. However, with potential for short
term training of cells and/or repeat rounds of convection, there
will be potential for runoff issues. Slight risk areas maintained
over the Upper OH Valley from northeast KY into southern OH where
FFG values are relatively low, and in the upslope region of the
Southern Appalachians from far northeast GA into the Upstate of SC
and western NC where heavy precip likely to focus in the region of
southerly low level flow. The slight risk areas fit well with the
axes of the HREF and RRFS means 2 and 3"+ probabilities.

Across the Southern Plains, a marginal risk area was introduced for
potential for additional convection Friday evening into the early
hours of Saturday. Additional shortwave energy expected to push
eastward into the Southern High Plains, supporting potential for
some organization to the associated convection late Friday into the
early hours of Saturday. Low confidence on details, with isolated
runoff issues possible where convection become organized.

Oravec


Day 2
Valid 12Z Sat May 23 2026 - 12Z Sun May 24 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF EASTERN
TEXAS AND WESTERN LOUISIANA...

Additional shortwave energy expected to move from far northeast
Mexico into southern and eastern Texas early Saturday, likely
setting the stage for another round of organized convection.
Building instability early Saturday, Mucape values reaching
2000-300 j/kg ahead of these height falls, in an axis of PW values
1.5-2.5 standard deviations above the mean, will support potential
for an organized line of convection to push across eastern and
southern TX Saturday morning into afternoon. The previous risk
areas were narrowed to better reflect the latest model qpf output
and the max RRFS 2 and 3"+ probability axes for the day 2 time period.

No significant changes made to the marginal risk area from the
Southern Appalachians into the Southeast. Southwest mid to upper
level flow with embedded shortwaves will continue across these
areas day 2. With PW values remaining well above average, 2 to 2.5+
standard deviations above the mean, additional widespread
scattered convection will likely produce locally heavy rainfall
totals. Both the HREF and RRFS show fairly high probabilities for
1"+/hr rainfall totals Saturday afternoon, supporting potential for
isolated runoff issues.

The marginal risk was also expanded northward from the previous
issuance into far eastern KS and large portions of MO to cover
areas the RRFS, GEM and FV3LAM are showing heavy rainfall totals day 2.

Oravec


Day 3
Valid 12Z Sun May 24 2026 - 12Z Mon May 25 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE UPPER
TEXAS COAST INTO SOUTHERN LOUISIANA...

A slow moving upper trof expected to amplify somewhat day 3 as it
pushes from eastern Texas into the Lower MS Valley. Similar to the
day 2 and day 3 period, there will continue to be an axis of much
above average PW values stretching from the Gulf Coast
northeastward into the Southeast/Southern to Central Appalachians.
There is a lot of spread day 3 with the QPF details, but still a
signal for widespread moderate to heavy rain potential in this
anomalous PW axis. A slight risk was maintained from the Upper TX
coast into southern LA, close to the WPC and NBM qpf max. This
covers the urban areas from Houston to New Orleans.

The marginal risk area was extended farther northeast through the
Southern to Central Appalachians where scattered convection likely
in the anomalous PW axis, supporting locally heavy rainfall
amounts and potential for isolated runoff issues.

Oravec
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 230808
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
408 AM EDT Sat May 23 2026

Day 1
Valid 12Z Sat May 23 2026 - 12Z Sun May 24 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR MUCH OF EASTERN
TEXAS AND WESTERN LOUISIANA...

Convection across the Southern Plains early this morning will
likely remain active in the post 1200 UTC period Saturday in an
overall favorable convective pattern over the Southern Plains into
the Lower MS Valley. There is a strong signal for widespread
heavy precip day 1 across eastern/southern TX into southern LA as
additional shortwave energy moving east northeastward from far
northeast Mexico into southern and eastern Texas early Saturday
enhances large scale uvvs. HREF and RRFS neighborhood probabilities
are high for 1 and 2"+ totals day 1 in the slight risk area.
Several of the latest CAMS, ARW2, GEM, NAMNEST and FV3LAM show
potential for a period of training of cells across the Upper TX
coast into southwest LA late morning into this afternoon. Across
these areas, the HREF and RRFS neighborhood probabilities are high
for 3"+ totals and the HREF probabilities high for 5"+ totals.
There is potential for these heavier totals affecting the urban
areas from Houston to Lake Charles, where an upgrade to a moderate
risk was considered and will be re-evaluated after viewing the 1200
UTC hi-res guidance as per collaboration with affected NWS WFOs.

No significant changes made to the marginal risk area from the
Southern Appalachians into the Southeast. Southwest mid to upper
level flow with embedded shortwaves will continue across these
areas day 1. With PW values remaining well above average, 2 to
2.5+ standard deviations above the mean, additional widespread
scattered convection will likely produce locally heavy rainfall
totals. Both the HREF and RRFS show scattered areas of fairly high probabilities for 1"+/hr rainfall totals Saturday afternoon,
supporting potential for isolated runoff issues.

Over the Upper OH Valley region, a marginal risk area was added for
potential for additional scattered convection and locally heavy
rains into this afternoon. This additional scattered heavy precip
will fall across areas that have received 1-2" of rain over the
past 24 hours, raising soil moisture and stream flows and lowering
FFG values. Isolated runoff issues possible across these areas.

Oravec


Day 2
Valid 12Z Sun May 24 2026 - 12Z Mon May 25 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE UPPER
TEXAS COAST INTO SOUTHWESTERN LOUISIANA...

A slow moving upper trof expected to amplify somewhat day 2 as it
pushes from eastern Texas into the Lower MS Valley. This will
likely help fire another round of convection in the vicinity of the
Upper TX coast, eastward into southern LA. At the moment, it
appears the best instability ahead of this next closed low will be
suppressed southward into the northern Gulf in the wake of the
active day 1 convection. This may support the heaviest rains being
shunted southward and off the coast day 2, as suggested by the RRFS
mean and the FV3LAM. There is still a lot of model spread, but WPC
qpf has trended south, with the heaviest offshore. Subsequently,
the previous slight risk area has been trimmed on the north end,
confined to the far Upper TX coast into southwest LA. There may be
overlap of the day 1 and day 2 heavy rain areas over the Upper TX
coast into southwest LA. However, at the moment, the risk level was
maintained as slight as there is still model spread with the day 2
heaviest qpf axis.

No significant changes made to the previous broad marginal risk
area extending northeastward from the Central Gulf Coast, across
the South and into the Southern to Central Appalachians. Similar
to the day 1 period, there will continue to be an axis of much
above average PW values stretching across these areas, with
embedded shortwaves in the broad southwesterly mid to upper level
flow, supporting widespread scattered convection, locally heavy
rains and isolated runoff issues.

Oravec


Day 3
Valid 12Z Mon May 25 2026 - 12Z Tue May 26 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
SOUTHERN APPALACHIANS...

A small slight risk area was introduced in the vicinity of the
Southern Appalachians from north Georgia into the Upstate of SC and
far southwestern NC. A very broad region of much above average PW
values, 2 to 2.5+ standard deviations above the mean, will stretch
from the Central gulf coast, northeastward across the South,
Tennessee Valley, Southern Appalachians and into the Southern Mid-
Atlantic during day 3. Similar to the day 2 period, broad south
southwesterly mid to upper level flow with embedded shortwaves will
support additional widespread scattered convection across these
areas. While locally heavy rains are likely across a large region
in this anomalous PW axis, there is model signal for concentration
of heavy precip into the upslope regions of the Southern
Appalachians, with a small slight risk area depicted here. Included
the Atlanta metro in the slight risk area given the sensitivity to
potential urban issues. There may be additional slight risk areas
in this anomalous PW axis depicted in future updates, but low
confidence with placement at this time.

Oravec
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 280734
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
334 AM EDT Thu May 28 2026

Day 1
Valid 12Z Thu May 28 2026 - 12Z Fri May 29 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS MUCH OF
THE SOUTHEAST TO MIDDLE MISSISSIPPI VALLEY, SOUTHEAST FLORIDA, AND
FOR PORTIONS OF THE NORTHWEST...

...Central Plains to Southeast...

A bit of an omega block pattern is shaping up across the CONUS
with a broad upper trough axis fixated over the Central and
Southern Plains with ridging in place over the top. This will cause
a rather chaotic flow under the mean trough and several smaller
mid- level perturbations basically "stuck" within the overall
trough axis. Ample instability with deep moisture presence will
certainly continue to support at least a scattered heavy rain
footprint across areas underneath influence of the trough.
Scattered elevated probabilities between 30-70% exists for
localized amounts >3" from KS all the way into the Southeast U.S.
with the maxima split between eastern KS to northern AR and the
Central Gulf coast. For KS/AR, parked underneath the upper trough,
upper forcing and stagnant flow are more favorable for heavier
rainfall totals. Maintaining a marginal risk at this time as the
heaviest rainfall over the past 12 or so hours was more southwest
of where the guidance is showing today and the rest of the region
is still somewhat dry and can probably support some heavier totals.
Along the Gulf Coast and into the Southeast, instability will be
maximized in this area with weak flow supporting slow- moving
convection and heavier rainfall over those isolated areas.
Antecedent conditions across much of this region are also very wet,
so it may not take much to cause issue. Given the still fairly
isolated nature, maintaining a broad marginal risk, with any
possible upgrades today stemming more from near term radar trends.

...Florida...

An active sea breeze pattern with weakening steering flow will
lead to periods of heavy rainfall across southeast Florida this
afternoon. Greatest concern remains over the South Florida metro
corridor from West Palm Beach to Miami. Latest HREF is robust with
showing greater than 50% probabilities for 3" in 24-hours, with
even some modest, albeit localized, probabilities for 5". This
correlates well with CAM guidance, with some indicating bullseyes
of greater than 3" within the larger QPF footprint. Locally
significant rainfall is likely in this relatively classic pattern
with ample moisture and instability present. A marginal risk
remains in effect across Southeast Florida.

...Washington/Oregon...

A deep upper level low over the West will allow for a broad axis
of diffluent flow across the interior Northwest. Precipitable water
values 1-1.5" are in the 90-90th percentile, and with sufficient
instability, should support convection capable of producing heavy
rainfall. Flooding and flash flooding are a concern for mainly the
more vulnerable areas - urban, small stream, and low lying areas.
HREF 24-hr probabilities for greater than 3" are between 40-70% for
especially the Oregon cascades. Given the favorable environment
though, a marginal risk extends all the way from far northern
California northward to the eastern half of Washington state. A
previous marginal risk for parts of the northern Rockies was
trimmed out for this update given the lack of QPF signal.

Santorelli


Day 2
Valid 12Z Fri May 29 2026 - 12Z Sat May 30 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
THE NORTHERN ROCKIES AS WELL AS MUCH OF THE SOUTHEAST TO MIDDLE
MISSISSIPPI VALLEY...

...Eastern Washington to Northern Rockies...

A marginal risk is in place across far northeast Washington to
northwest Montana due to an increase in the heavy rainfall signal
for this period as the upper low over the West on Day 1, pivots
slightly northeastward, placing this region in an area with better
upper forcing and advection of moisture. The presence of anomalous
moisture and some instability may present a threat for localized
heavy rainfall and flash flooding, especially for burn scar
locations within this region.

...Middle Mississippi Valley to the Southeast...

Strong Canadian high pressure pressing in from the north will
allow for a slow moving cold front to press south over the course
of Thursday into Friday with convection likely to spawn along and
ahead of the front and dry air advecting behind the front leading
to a quick cutoff of activity. The front will arc back into the
Tennessee Valley to Middle Mississippi Valley, supported by the
persistent troughing over the south-central Plains. A moist and
unstable environment near and south of this front will support
scattered convection, with some heavier cells likely within the
pattern. It is still too hard to pick out any discernible areas of
interest, so maintained a very broad marginal risk over this area
which is quite wet and will continue to be in the Day 1 period.

Santorelli


Day 3
Valid 12Z Sat May 30 2026 - 12Z Sun May 31 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS THE
NORTHERN ROCKIES TO HIGH PLAINS AND THE SOUTHEAST...

...Northern Rockies to High Plains...

The upper level low over the West during the Day 1 and 2 periods
will weaken and shift northeastward, moving over the Northern
Rockies to High Plains region on Day 3/Saturday. Moisture anomalies
will continue to be in the 90-90th percentile, supporting moderate
to heavy rainfall, with widespread QPF greater than 0.5-1" likely
across western and central Montana. There may not be a lot of
instability to work with, so any flood or flash flood threats
should be mainly localized with particular attention to burn scar
locations. A fairly broad marginal risk is in place across much of
western and central Montana, into parts of northern Wyoming as well.

...Southeast...

Same story as Days 1 and 2, with ample moisture and instability
present near and south of a cold front that may stall over the
region on Saturday supporting convection, across much of the
Southeast. Some of this region, especially western parts of South
Carolina and into the Appalachians has been very wet as of late and
is well primed, so may be more favorable for flooding concerns.
The marginal risk though continues towards the coast due to the
presence of a weak frontal wave in the region. The Marginal Risk
extends from the Southeast coast, westward into northeast Alabama
and southeast Tennessee.

Santorelli
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)

FOUS30 KWBC 290829
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
429 AM EDT Fri May 29 2026

Day 1
Valid 12Z Fri May 29 2026 - 12Z Sat May 30 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHEAST...

Largely maintained the previous Slight Risk area that was introduced
in the Southeast US. A sheared 500mb vorticity maximum approaching
from the west will be encountering a moist airmass with increasing
amount of instability later during the day and evening. The latest
numerical guidance kept expected precipitable water values in the
2 to 2.25 inch range along and south of a quasi-stationary front
draped across the region from the TN Valley to the SC coast.
Instability will be highest over AL on east into central and
southern GA with MUCAPE between 1,000-2,000 J/kg most often. MUCAPE
up to 1,000 J/kg will be available later tonight from the Savannah
River to coastal SC. This combination should be enough to support
and sustain localized rainfall rates in excess of 2 inches per hour
where warm rain processes predominate from eastern AL eastward to
the Savannah River this afternoon and tonight.

...Middle Mississippi Valley to the Southeast...

The western portion of the front affecting the Southeast US will
extend into portions of the Middle Mississippi Valley and provide
the focus for showers and thunderstorms...some of which may produce
locally heavy rainfall from the Tennessee Valley into the Middle
Mississippi Valley into tonight.

...Eastern Washington to Northern Rockies...

A marginal risk remained in place across far northeast Washington
to northwest Montana due to an increase in the heavy rainfall
signal for this period as an upper low over the West on Day 1
places this region in an area with better upper forcing and
advection of moisture. The presence of anomalous moisture and some
instability may present a threat for localized heavy rainfall and
flash flooding, especially for burn scar locations within this region.

Bann


Day 2
Valid 12Z Sat May 30 2026 - 12Z Sun May 31 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS THE
NORTHERN ROCKIES TO HIGH PLAINS AND THE SOUTHEAST...

...Southeast...

Latest numerical guidance has shifted a majority of the rainfall
eastward enough compared with previous runs to preclude an upgrade
to a Slight risk. In addition...the spread of model
guidance both in terms of placement and amounts precluded an
upgrade. As mentioned previously...some of the region, especially
western parts of South Carolina and into the Appalachians, has
been very wet as of late and is well primed, so may by more
vulnerable to flooding concerns.

...Northern Rockies to High Plains...

The upper level low over the West during the Day 1 period will
weaken and shift northeastward, moving over the Northern Rockies to
High Plains region on Saturday. Moisture anomalies will continue
to be in the 90-90th percentile, supporting moderate to heavy
rainfall, with widespread QPF greater than 0.5-1" likely across
western and central Montana. There may not be a lot of instability
to work with, so any flood or flash flood threats should be mainly
localized with particular attention to burn scar locations. A
fairly broad marginal risk remained in place across much of
western and central Montana, into parts of northern Wyoming as well.

Bann


Day 3
Valid 12Z Sun May 31 2026 - 12Z Mon Jun 01 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE NORTHERN ROCKIES AND THE SOUTHEAST UNITED STATES...

...Northern Rockies and Adjacent High Plains...
The upper level low which has been supporting the prolonged wet
period over the Northern Rockies will continue to move northward
across Montana slowly on Sunday. This results in surface low
pressure and associated surface front to makes its way out over the
Plains and gradually weaken while the mid and upper level
circulation keeps precipitation lingering over Montana and far
northern Wyoming. Moisture remains anomalously high but instability
still looks to be dependent upon cloud cover. As in the Day 2
period...any flood or flash flood threats should be mainly
localized with particular attention to burn scar locations.

...Southeast...

Until surface high pressure builds far enough southward into the
Southeast states to decrease coverage of lingering convection on
Sunday evening...the antecedent conditions keep a risk of flooding
concerns over the area.

Bann
$$
--- MultiMail/DOS
* Origin: Project Scorpio TEST (618:250/6)