FOUS30 KWBC 080822
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
322 AM EST Sat Mar 8 2025

Day 1
Valid 12Z Sat Mar 08 2025 - 12Z Sun Mar 09 2025

...A MARGINAL RISK OF EXCESSIVE RAINFALL EXISTS FOR PORTIONS OF THE
CENTRAL GULF COAST...

19Z Update...
No significant changes were made to the previous outlook area.

Previous discussion...
There will be an increasing chance for showers and thunderstorms
capable of producing localized downpours later today and tonight
across portions of the central Gulf coast. There could be some
rainfall rates that exceed one inch per hour as a fairly potent 
shortwave trough/upper low makes its way from the Southwest U.S. 
into the Southern Plains by early Sunday morning. South to 
southwesterly low level flow ahead of the mid- level energy will 
start to draw moisture northward...with precipitable water values 
increasing into the range between 1.50 and 1.75 inches by later
this afternoon...although model guidance still suggests that the
higher rainfall rates probably do not develop until the better 
upper level support approaches and a well-defined cold front nears
the coast later tonight/early Sunday morning, Given the Flash Flood
Guidance in the region...not expecting more than isolated problems
given the 08/00Z HREF neighborhood probabilities for amounts
exceeding an inch of accumulation in one hour.

Bann


Day 2
Valid 12Z Sun Mar 09 2025 - 12Z Mon Mar 10 2025

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

Considerable spread remains in the numerical guidance in term of
placement...but enough QPF along the path of a well-defined
shortwave to keep a Marginal risk in place. The 08/00Z GFS 
started out in fairly good agreement with other models but becomes
a northerly outlier as it gets drawn northward by northern stream
energy...while the 08/00Z NAM continued to indicate heavier
rainfall with a greater threat for flash flooding farther north. 
Less weight for now was given to these solutions, keeping the 
deterministic QPF and the Marginal Risk for excessive rainfall more
in line with the more southerly ECMWF, CMC, and UKMET guidance. In
large part...there were few changes needed given good continuity
with the WPC deterministic QPF and the consensus QPF of the non-
NCEP guidance. 

Bann


Day 3
Valid 12Z Mon Mar 10 2025 - 12Z Tue Mar 11 2025

The probability of rainfall exceeding Flash Flood Guidance is less
than 5 percent. 

Bann

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