FOUS30 KWBC 072322
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
622 PM EST Sat Mar 7 2026

Day 1
Valid 01Z Sun Mar 08 2026 - 12Z Sun Mar 08 2026

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PARTS OF
THE CENTRAL GULF COAST...


Mainly due to convective progression, there has been a significant
shrinking in both the Marginal and Slight Risk areas. The 
mesoscale guidance most suggests that heavy rain issues from 01z 
onward lie from the Upper TX Coast eastward towards Mobile. The 
degree of moisture, instability, and effective bulk shear available
near and equatorward of a cold front continues to support the 
potential for hourly rain amounts to 2.5" with local totals to 4". 

While not depicted as a separate Slight Risk, mainly because it's 
out in Brush Country, portions of interior South TX have a chance 
in the very near term for heavy rainfall as well. Although they are
included in the Marginal Risk category, it's a higher end Marginal
Risk in that area. Overall, much of the rainfall expected is 
beneficial, relieving long term drought conditions. The intensity 
of organized convection and where storms can train and/or merge 
would threaten urban areas most. 

Roth


Day 2
Valid 12Z Sun Mar 08 2026 - 12Z Mon Mar 09 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE GULF COAST REGION...

2100 UTC update:

No changes made to the previous marginal risk area across the Gulf
coast region.

Oravec

Previous discussion:

Deep moisture...instability and the risk of excessive rainfall
should be confined to a shrinking area south of an approaching
cold front on Sunday. Model guidance showed a corresponding
decrease in QPF and spaghetti plots from the SREF and the GEFS
maintaining a few members kept neighborhood probabilities of 1 inch
or greater confined from Louisiana into Georgia with greatest
clustering from southern Mississippi into central and southern
Alabama with QPF spaghetti plots showing few members at 2 inch
amounts in 24 hours from either the SREF ir GEFS. In this portion
of the Marginal risk...there was good agreement between WPC and the
CSU machine learning first-guess ERO. The WPC Marginal Risk area
extended west along the Louisiana and Upper Texas coast if
deference to the HREF and RRFS runs which lingered some 1+ in per
hour rainfall along the coast and even some 2 inch per 6 hour
lingering through at least 08/18Z. In addition...Gulf moisture
starts to return northward over southwestern Texas later in the
period...also supporting a westward expansion.

Bann


Day 3
Valid 12Z Mon Mar 09 2026 - 12Z Tue Mar 10 2026

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL OVER PORTIONS OF
THE LOWER MISSISSIPPI VALLEY INTO THE UPPER TENNESSEE VALLEY...

2100 UTC update:

Only some minor changes made to the marginal risk area from the
Lower Mississippi Valley into the Upper Tennessee Valley. Changes
made were to cover the latest qpf spread for locally heavy precip
totals day 3 across these regions.

Oravec

Previous discussion:

The front which had been moving from west to east in the Day 1 and
Day 2 period will slow its forward motion and become oriented along
a west to east axis on Monday and the start to inch northward
Monday afternoon and Monday night. There is a wide range of
solutions in where convection could fire along that boundary which
limits confidence. However...confidence is higher in the occurrence
of showers and thunderstorms occurring rather than details of where
that could happen given precipitable water values approaching 1.75
inches ready to to be lifted isentropically above the front as low
level flow becomes southerly. The area should become better focused
in subsequent outlooks.


Bann
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