Flash Flood Guidance
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AWUS01 KWNH 051747
FFGMPD
MSZ000-LAZ000-TXZ000-052345-
Mesoscale Precipitation Discussion 1209
NWS Weather Prediction Center College Park MD
146 PM EDT Sat Sep 05 2026
Areas affected...portions of Southwest LA & Southeast TX
Concerning...Heavy rainfall...Flash flooding possible
Valid 051745Z - 052345Z
Summary...Showers and thunderstorms with heavy rainfall are
becoming numerous across the region. Hourly rain amounts to 3"
with local totals to 5", particularly in urban areas and soils
still partially saturated by Edouard.
Discussion...Showers and thunderstorms are increasing in number
across Southwest LA & Southeast TX. This is occurring near a zone
of 850 hPa confluence. Precipitable water values are 2.25-2.5".
Effective bulk shear is <25 kts, leading to pulse convection. ML
CAPE is ~2000 J/kg.
GFS-based Galvez-Davison Index values imply that convection could
continue to increase in coverage through 21z before starting to
starting to fade thereafter. This is supported by 12z HREF
guidance. Due to the parameters above, hourly rain amounts to 3"
with local totals to 5" are possible where cells merge or manage
to train. This would be most problematic in urban areas and
locations with soils remaining at least partially saturated from
Edouard`s deluge a few days ago.
Roth
...Please see www.wpc.ncep.noaa.gov for graphic product...
ATTN...WFO...CRP...EWX...FWD...HGX...JAN...LCH...LIX...SHV...
ATTN...RFC...FWR...ORN...NWC...
LAT...LON 32469462 31379275 30899044 29749097 29409190
29539385 28669566 28349692 29719685 31349648
32309565