FOUS30 KWBC 060830
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
430 AM EDT Wed May 6 2026

Day 1
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...

On-going convection at the start of the Day 1 period will linger
over portions of Arkansas. northern Mississippi and adjacent
portions of Tennessee as a cold front progresses into a most and
unstable atmosphere. Given the alignment of the storm motion and
the boundary...some training will continue with localized rainfall
totals of 1 to 2 inches before convection wanes. WPC Mesoscale
Precipitation Discussion was issued covering this area valid
through 1320Z.

The high-resolution guidance continued to struggle at eh 06/00Z
production cycle and continued with their earlier idea of bimodal
distribution to the heavy rainfall while coarser scale models
tended to have a more uniform distribution of rainfall but with
different orientations. Both the Latest HREF/RRFS guidance showed
some 15+ percent neighborhood probabilities of 24 hr QPF exceeding
10 year ARIs over portions of Mississippi and Alabama. This led to
a southward expansion of the Slight Risk area. Elsewhere...rainfall
amounts of 1 to 2 inches in an hour should be reachable within the
Slight Risk area but the signals as to where this happens are not
as strong. With increasing input from the convective allowing
models...further increases in expected rainfall amounts and better
agreement are possible which might result in an upgrade with future updates.

Bann


Day 2
Valid 12Z Thu May 07 2026 - 12Z Fri May 08 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
TEXAS EASTWARD TO GULF COAST REGION AND SOUTHEAST UNITED STATES...

Abundant moisture along a stalled frontal boundary on Thursday
will support additional thunderstorm formation along the front.
Rapidly weakening forcing at the surface and aloft will greatly
diminish convective coverage and restrict the parameters favorable
for heavy to excessive rainfall along the Gulf Coast and into
central Georgia and South Carolina. Given differences in the way
numerical guidance has in terms of how fast the front is
progressing...there was some continued adjustments to the placement
of the Marginal risk area.

South TX Brush Country...

An upper low with an associated surface boundary approaching the
region should lead to increasing chances for showers and
thunderstorms. Expectations are that most of the convection in this
time frame will remain west of the international border but there
are enough models showing some storms making east of the Rio Grande
River with isolated heavier amounts and inferred rainfall rates
that could lead to isolated flooding concerns during the late day/evening.

Bann


Day 3
Valid 12Z Fri May 08 2026 - 12Z Sat May 09 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE LOWER- AND CENTRAL TEXAS COAST ON FRIDAY...

Attention shifts to the Lower Texas coast for a risk of excessive
rainfall as shortwave energy nears the region from the southern
Great Basin and northern Mexico. Low level flow backs in response
to the approaching shortwave which results in precipitable water
values to exceed 2 inches along the immediate coastline. This
occurs at the same time flow aloft is expected to become
increasingly difluent and when the CAPE is approaching 1000 J per
kg. This should result in growing coverage of convection that will
be capable of producing rainfall rates sufficiently high to result
in isolated instances of flash flooding.

Bann

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

The risk of excessive rainfall will be focused along the low-level
boundary that builds into the region on Day 2 and stalls along a
west to east axis. Precipitable water values in excessive of 1.5
inches should be pooling along the boundary on Friday...with higher precipitable water values returning northward later in the day on
Friday and through Friday night/early Saturday morning.

Southern stream shortwave energy become southerly during the day
and increases.

The Marginal risk area is conditional in the sense that a Slight
could be needed depending on observed rainfall on Day 2, the
degree of overlap with Day 3 QPF and the amount of urbanization.

Bann
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/10)

FOUS30 KWBC 070810
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
410 AM EDT Thu May 7 2026

Day 1
Valid 12Z Thu May 07 2026 - 12Z Fri May 08 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM SOUTHERN
ALABAMA AND THE FLORIDA PANHANDLE TO SOUTHERN GEORGIA...

...Gulf Coast/Southeast...
While the overall coverage and intensity will likely be
diminishing, showers and storms will remain ongoing with the
potential for additional heavy amounts and flash flooding concerns
beyond 12Z this morning. A Marginal Risk was maintained across
portions of southern Alabama, the Florida Panhandle, and southern
Georgia. A 40-50 kt southwesterly low level jet ahead of an
approaching front will continue to support PWs around 2 inches,
which along with favorable upper jet forcing will likely support
the continuation of some storms with heavy rainfall rates well into
the morning. Both the HREF and RRFS indicate that localized
additional amounts of 1-2+ inches are likely. This is expected to
occur mostly, if not entirely, within the first 6 hours of the
period before the deepest moisture and the better forcing moves downstream.

...Rio Grande Valley...
The Marginal Risk has been removed. While a weak surface low and
approaching shortwave trough will support convective development
over the mountains of Mexico, the majority of the models indicate
that the bulk of the heavy rainfall will remain south of the
international border. While an isolated heavy total remains
possible, and the threat for flash flooding across South Texas is
non-zero, the coverage is no longer expected to meet Marginal Risk criteria.

Pereira


Day 2
Valid 12Z Fri May 08 2026 - 12Z Sat May 09 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM SOUTH TEXAS
GULF COAST THROUGH THE LOWER MISSISSIPPI VALLEY...

The synoptic pattern on Friday will characterized by the return of
deep moisture as a previously stalled front, lingering along the
Gulf Coast begins to lift northward as a warm front. PWs are
forecast to climb above 1.75 inches from South Texas through the
lower Mississippi Valley, providing an ample reservoir for heavy
rainfall. This moisture, along with an upper level low moving into
West Texas and downstream shortwave energy/upper jet forcing, are
expected to support numerous showers and storms with the potential
for heavy rates. However, while the environment is expected to be
favorable for numerous showers and storms to develop, confidence in
the placement of the heaviest rainfall has diminished with this
cycle, with significant model spread regarding where the most
intense convective clusters will organize. Therefore, the Slight
Risk that was previously carried from southeastern Texas through
the lower Mississippi Valley has been removed for now. The
reintroduction of a Slight Risk may be warranted in future updates, particularly farther southwest across South Texas closer to the
ejecting upper low/shortwave, but predictability is too low to
maintain the higher category. For now, will maintain a broad
Marginal Risk extending from South Texas to southern Mississippi.

Pereira


Day 3
Valid 12Z Sat May 09 2026 - 12Z Sun May 10 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
THE LOWER MISSISSIPPI VALLEY AND THE CENTRAL GULF COAST...

The previously noted upper level low moving across southern Texas
on Day 2 will continue to eject east, moving along the central Gulf
Coast into the Southeast -- deamplifying as it becomes embedded
within the base of a broad upper trough centered over the central-
eastern U.S. Deep moisture remaining ahead of this wave and along a
slow-moving boundary will continue to fuel shower and storm
development capable of producing heavy rainfall. Similar to Day 2,
confidence was lacking for any upgrades beyond a Marginal Risk.
However, should the models start to move into better agreement, an
upgrade may be warranted in future updates -- especially if the
guidance begins to show a growing signal for heavy amounts across
areas impacted by recent heavy rains.

Pereira
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/10)

FOUS30 KWBC 080800
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
400 AM EDT Fri May 8 2026

Day 1
Valid 12Z Fri May 08 2026 - 12Z Sat May 09 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
SOUTHEASTERN LOUISIANA AND SOUTHERN MISSISSIPPI...

...Lower Mississippi Valley/Central Gulf Coast...
A robust moisture pool is expected to deepen along the central Gulf
Coast today as southwesterly winds amplify ahead of energy moving
out of eastern Texas and the northwestern Gulf. This flow will
support PWs climbing to around 2 inches along a slow-moving front,
or more than 2.5 std dev above normal. The majority of the CAMs
are in good agreement indicating a corridor of training convection
developing by the afternoon across southeastern Louisiana and
southern Mississippi. Given the high moisture content and potential
for training, localized totals of 2-3+ inches are possible. High
hourly rates within these training storms will pose a risk for
flash flooding, particularly in low-lying and urban areas, with
the highest potential impact centered along the I-10 corridor. The
introduced Slight Risk area reflects high neighborhood
probabilities shown by both the HREF and RRFS for amounts exceeding 2 inches.

...South Texas...
Farther west, a well-defined mid-to-upper level shortwave/low
moving through northern Mexico into West Texas will provide
increasing ascent. Moist southerly flow interacting with this
feature and upslope into the Sierra Madre Oriental will support
storms developing over northeastern Mexico. While much of this
activity may remain south of the international border, there are
some hi-res members that show some of these convective clusters
moving into South Texas. Though model spread is higher in this
region, both the HREF and RRFS indicate that localized totals
exceeding 2 inches are possible. Therefore, a Marginal Risk was
maintained to account for this potential.

Pereira


Day 2
Valid 12Z Sat May 09 2026 - 12Z Sun May 10 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE CENTRAL
GULF COAST INTO THE SOUTHEAST...

The previously noted shortwave moving into West Texas on Day 1 is
forecast to move eastward along the central Gulf Coast on Saturday.
While lingering deep moisture will remain in place, the synoptic
signal for organized and widespread heavy rainfall becomes
significantly more diffuse. Current model guidance lacks a
concentrated signal for high-end totals, suggesting a more isolated
or low-end flash flood threat. Given the environment and the
potential for antecedent conditions driven the previous day's heavy
rains, the current Marginal Risk was maintained for this cycle. But
should model trends continue to show a lack of organization, this
area may be discontinued in future updates.

Pereira


Day 3
Valid 12Z Sun May 10 2026 - 12Z Mon May 11 2026

...THERE IS A MARGINAL RISK FOR EXCESSIVE RAINFALL ACROSS PORTIONS
OF NORTHEASTERN TEXAS, SOUTHEASTERN OKLAHOMA, SOUTHERN ARKANSAS,
AND NORTHERN LOUISIANA...

Shortwave energy diving into the base of broader scale trough will
drive a cold front southward across the region. Southerly flow
ahead of the boundary will boost PWs to over 1.5 inches. This
moisture, combined with favorable upper jet forcing, will support
storms developing along and ahead of the front. While model spread
is currently too high to support a higher risk area and the signal
for widespread heavy totals remains muted, locally intense rates
along with some areas of repeating cells could result in isolated
flash flooding.

Pereira
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/10)

FOUS30 KWBC 150736
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
336 AM EDT Fri May 15 2026

Day 1
Valid 12Z Fri May 15 2026 - 12Z Sat May 16 2026

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

Wegman


Day 2
Valid 12Z Sat May 16 2026 - 12Z Sun May 17 2026

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

Convection developing along a warm front draped across the Ohio
Valley could form over more sensitive urban areas on Saturday
afternoon. Soils across the Ohio Valley have sufficiently dried out
from the last round of organized heavy rain, so any flood threat
would likely be tied to the urban areas. The CAMs that cover this
time period are mostly suggesting any convection will quickly
develop into fast-moving line segments. Further, where those line
segments form is highly uncertain. Thus, the area will be monitored
for a potential future Marginal Risk, but for now uncertainty is
too great to draw one in at this time.

Wegman


Day 3
Valid 12Z Sun May 17 2026 - 12Z Mon May 18 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE UPPER MIDWEST/UPPER MISSISSIPPI VALLEY...

A digging longwave upper level trough will eject several rounds of
shortwave energy northeastward ahead of the trough from the central
Plains and into the Upper Midwest on Sunday. The nose of a stout
low-level jet will provide ample moisture for any storms that
develop to feed on. Morning rain will douse the area as the dying
remnants of an MCS move across the Marginal Risk area. There will
likely be a break in any rainfall for much of the day as the
atmosphere recharges and instability advects north ahead of an
approaching area of low pressure. Numerous showers and
thunderstorms will form in a line very late in the day, near
sunset, with the storms moving sufficiently parallel/along the line
to introduce a training threat across the Marginal Risk area. Much
of the heaviest rain and the greatest flash flooding threat will
occur Sunday evening before the surface low pressure propagates
into Minnesota and allows the convection to have a faster push
towards the east. The increasing forward speed of the line will
diminish the flooding threat somewhat after midnight, through
convection ahead of the low could still affect portions of northern
Minnesota well into the overnight. Dry antecedent soil conditions
should generally mitigate the flooding risk, so the inherited
Marginal Risk was left largely unchanged. Some trimming on both the
west and east sides were done to highlight the increasing
confidence that the axis of heaviest rainfall will occur generally
across Minnesota, potentially spilling over to adjacent areas of
the neighboring states.

Wegman
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/10)

FOUS30 KWBC 160737
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
337 AM EDT Sat May 16 2026

Day 1
Valid 12Z Sat May 16 2026 - 12Z Sun May 17 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE LOWER TO MID OHIO VALLEY AS WELL AS PORTIONS OF THE CENTRAL PLAINS...

...Lower to Mid Ohio Valley...

Areas of convection that will form along a warm front at the nose
of a low-level jet are expected to develop during peak heating
today across the lower to mid Ohio Valley. While the main branch of
the low level jet remains oriented south to north over the Plains,
the side branch over the Ohio Valley will be oriented southwest to
northeast. This will promote training storms with backbuilding
convection, while the primary storm movement is towards the
east. Training storms are most likely to develop in the Marginal
Risk area. Despite very dry soils over the region, which will limit
the flash flooding risk, some urban areas are threatened with the
possibility of training storms, so the Marginal remains in place.

...Central Plains...

During the early evening hours, showers and thunderstorms will
develop along the nose of a robust low level jet transporting
abundant moisture and instability north from the Gulf into the
central Plains. A warm front at the leading edge of the warm, moist
air mass will interact with a strengthening upper level shortwave
and a developing surface low over southwest Kansas to support the
convective activity. While some of the convection will develop into
a highly progressive bowing segment, it's likely that the southern
end of the bow will get "stuck" and remain largely in place as
additional convection backbuilds westward, generally along the
Iowa/Missouri border. Repeating rounds of convection are possible,
and likely to be of somewhat greater vigor than the ongoing
convection across Iowa. Any overlap of the convection this evening
with the rainfall footprint of the ongoing storms present over
central Iowa could also locally increase the flash flooding risk.
However, at the moment any overlap should be minimal, as the
strongest storms with the greatest flash flooding risk are expected
along the Missouri/Iowa border, which did not see any meaningful
rain last night. Thus, the Marginal remains in place as soils in
the region remain very dry.

...Elsewhere...

In between the areas of storms over eastern Missouri/western
Illinois, a "break" is likely to remain, separating the footprints
of the two areas of storms. With minimal rainfall expected along
the Mississippi River near St. Louis, the inherited Marginal was
removed, leaving two separate Marginal Risk areas.

Wegman


Day 2
Valid 12Z Sun May 17 2026 - 12Z Mon May 18 2026

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

A robust low level jet feeding plentiful moisture ahead of a
developing low over the Plains will provide the moisture and
instability needed for numerous thunderstorms across a large
portion of the upper Midwest from far eastern Nebraska northeast
through the Arrowhead of Minnesota. The storms are likely to be
their strongest Sunday night. This will coincide with the diurnal
strengthening of the low level jet. Clusters of showers and storms
will develop with increasing forcing ahead of a slow moving upper
level trough over the High Plains. The storms are likely to train
as several rounds of upper level energy support several rounds of
storm clusters. Much of Iowa saw beneficial rains overnight
tonight, such that by Sunday night, the soils will still have some
moisture left over. Urban concerns, especially in and around the
Twin Cities could also locally increase the flash flooding threat.
Significant dry time in between the storms should limit the
flooding threat such that the inherited Marginal still looks good,
and few changes were needed.

Wegman


Day 3
Valid 12Z Mon May 18 2026 - 12Z Tue May 19 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM PORTIONS OF
THE CENTRAL PLAINS THROUGH THE UPPER MIDWEST...

An upper level trough that has been "stuck" over the northern High
Plains for a few days will finally begin to eject across the
northern Plains on Monday. This will occur because a strong
shortwave on its southern edge near the 4 Corners region will help
to nudge the trough eastward. This strong shortwave will run into
plentiful Gulf moisture that will continue streaming northward
across the middle of the country, as it has been doing for the past
several days. A cold front on the northwestern boundary of that low
level jet will provide ample surface forcing for the storms. The
initial meeting of the warm, moist air mass to the east and the
cooler, drier air mass over the northern Plains will be along the
Missouri River from far northeastern Kansas north across much of
western Iowa. This will be the corridor where the heaviest rainfall
totals are expected on Monday through Monday night. This is the
same region that will have been hit by multiple days of scattered
heavy rainfall. By Day 3/Monday, soils should be much closer to
saturation. Thus, with the greatest rainfall amounts areally
expected on Monday, the flooding threat increases into the Slight
Risk category. Any storms that form will continue to rapidly
progress northeastward into the upper Mississippi Valley. This area
too will have seen multiple days of storms by Monday. Thus,
expecting wetter than normal soil conditions in most areas by
Monday, the Slight Risk area was expanded northward to cover the
upper Mississippi Valley to the western tip of Lake Superior.

There remains some uncertainty as to where the axis of heaviest
rainfall will set up. Thus, the surrounding Marginal covers
extensive real estate east of the Slight from northern Illinois
north through much of the U.P. of Michigan. While expected rainfall
totals are lower in this region, greater urban concerns are present
in this area, which supports the Marginal Risk.

Wegman
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/10)

FOUS30 KWBC 170703
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
303 AM EDT Sun May 17 2026

Day 1
Valid 12Z Sun May 17 2026 - 12Z Mon May 18 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF
THE CENTRAL PLAINS TO THE UPPER MIDWEST...

A pair of shortwave troughs tracking northeast on the downwind side
of a slow moving longwave trough over the Intermountain West will
provide upper level forcing for several rounds of thunderstorms to
impact a large area from Kansas through the upper Great Lakes. A
fully open Gulf and associated moisture plume will continue to
advect northward up the Plains and Mississippi River. This will
keep PWATs consistently above 1.25 inches, with many areas above
1.5 inches. This influx of moisture will support and instability
will support both storms capable of heavy rainfall, as well as
development and redevelopment of storms in this favorable weather
regime. For the most part, due to fast upper level flow, the storms
will likely organize into fast moving lines/segments, which should
work to keep rainfall totals manageable in any one area. The
greatest area of concern stretches from southeastern Nebraska east
along the Iowa/Missouri border, where multiple inches of rain have
fallen overnight last night. Thus, any backbuilding or holdups in
any lines of storms could have outsized flooding impacts. A short-
fused Slight may be needed once again in this general area if
rainfall totals today come up further.

For southeastern Louisiana, the inherited MRGL was removed. Nearly
all of the guidance shows only light showers expected to impact
that area, with only a one or two showing one isolated storm.
Further, high FFGs should preclude any flooding even if that one
storm does form.

Wegman


Day 2
Valid 12Z Mon May 18 2026 - 12Z Tue May 19 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FROM THE CENTRAL
PLAINS TO THE UPPER MISSISSIPPI VALLEY...

Relatively few changes were needed to the outlook for this likely
busiest day of the upcoming three. A strong shortwave making up the
base of the longwave trough over the Rockies will finally eject out
over the Plains on Monday. As that shortwave interacts with
plentiful Gulf moisture streaming north up the Plains, renewed
lines of showers and storms are expected to develop across the
Slight Risk area. Since the storm motion will be towards the
northeast, largely parallel to the moisture and instability plume
emanating from the Gulf, backbuilding will be a greater
possibility than in previous days. Several of the high resolution
model guidance show that there could be multiple rounds of storms
to impact the area from northeast Kansas through southwestern Iowa,
especially in the late afternoon through the first half of the
overnight. This area is currently getting very hard-hit with heavy
rain from a very slow-moving MCS that has been producing multiple
inch per hour rainfall rates and numerous instances of flash
flooding. Thus, the soils have become very saturated in some areas.
Following potential heavy rain during the day 1/Sunday period,
much more rain is expected in this region again on Monday. A
higher-end Slight covers the aforementioned region from northeast
Kansas through the southwest corner of Iowa. Should multiple inch
per hour rates materialize again in this same region, a Moderate
Risk upgrade will need to be considered with future updates.

Wegman


Day 3
Valid 12Z Tue May 19 2026 - 12Z Wed May 20 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE SOUTHERN
PLAINS THROUGH THE LOWER OHIO VALLEY...

The inherited Slight Risk for the southeastern half of Oklahoma was
removed with this update. Guidance has been understandably
struggling with the placement of expected rainfall/convection
across this region. Since there's excellent agreement that the axis
of heaviest rainfall will shift well south of the area expected to
be hit with heavy rain in days 1 and 2, the region of greatest
impact is an area where soils have dried out and will likely be
very receptive to beneficial rainfall. Since guidance is in poor
agreement on where the storms will be most persistent, instead
broad brushing much of the Marginal Risk area with anywhere from a
half inch to 1.25 inches, have opted to leave the large Marginal in
place. None of the guidance particularly favors southeastern
Oklahoma for any heavier amounts that anywhere else, especially
further south into Texas. Expect that should a new Slight be needed
with a future update, it will be over a portion and not into
Oklahoma, which sits at the back/northwestern edge of the heavier rain axis.

Wegman
$$
--- SBBSecho 3.28-Linux
* Origin: Capitol City Online (618:250/10)