AWUS01 KWNH 041222
FFGMPD
TXZ000-041821-

Mesoscale Precipitation Discussion 0974
NWS Weather Prediction Center College Park MD
821 AM EDT Wed Sep 04 2024

Areas affected...south Texas through the middle Texas coast

Concerning...Heavy rainfall...Flash flooding possible

Valid 041221Z - 041821Z

Summary...Persistent onshore flow was contributing to scattered
areas of heavy rainfall especially along coastal areas near Corpus
Christi.  Isolated instances of flash flooding are expected to
continue through 18Z/1p CDT today.

Discussion...Deep, slow-moving convection continues to drift
onshore from northwestern Gulf of Mexico waters into the
discussion area.  The onshore flow regime is being maintained due
to a weak surface low near Brownsville and east-southeasterly
850mb flow on the northeastern side of that cyclone.  That
enhancement of low-level flow was maintaining strong buoyancy
(1500 J/kg MLCAPE) along and just inland from Texas coastal areas,
while low-level convergence was promoting continued updrafts amid
a very moist airmass (2.5+ inch PW values).  This regime was
continuing to support local 1-3 inch/hr rain rates at times
especially with more persistent convection as noted with
convection near Port Aransas and just north of Brownsville.

The ongoing scenario supporting flash flooding will evolve very
slowly today.  Spots of 1-3 inch/hr rain rates remain likely as
convection slowly streams westward toward Texas coastal areas
today.  These heavier rain rates could also materialize as far
north as the Galveston area as well. FFG thresholds vary
spatially, and generally range from 1.5-3.5 inches/hr. 
Isolated/localized flash flood potential is expected to persist
through at least 18Z today in this regime, with the most
pronounced threat existing where 1) >1 hour of heavier rainfall
persists and/or 2) in low-lying/sensitive areas.

Cook

ATTN...WFO...BRO...CRP...HGX...LCH...

ATTN...RFC...WGRFC...NWC...

LAT...LON   29899443 29479412 28739523 28229646 27159711 
            26169708 25819715 25769774 26399870 27419880 
            28479787 29529608 
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