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
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