Flash Flood Guidance
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Issued by NWS
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AWUS01 KWNH 010002
FFGMPD
TXZ000-010300-
Mesoscale Precipitation Discussion 0361
NWS Weather Prediction Center College Park MD
801 PM EDT Fri May 31 2024
Areas affected...South Central Texas
Concerning...Heavy rainfall...Flash flooding possible
Valid 010001Z - 010300Z
SUMMARY... Persistent supercells capable of 2.5 inch per hour
rainfall rates may cause flash flooding in portions of south
central Texas.
DISCUSSION... A cold front/convergence zone moving southward
across east Texas is colliding with southerly flow of Gulf
moisture across the middle/western part of of the state. A small
area of strong supercells on the boundary is tracking south along
the front. These cells have a history of causing flash flooding
with as high as 2.5 inch per hour rates. PWATs increase to the
south over 1.5 inches, and CAPE values as high as 3,000 J/kg are
ahead of the supercells. This suggests the cells should continue
to remain strong as they track south-southeastward. Flash flood
guidance in this area says that due to recent heavy rainfall, 1.5
to 2 inch per hour rainfall rates are all that are needed to
exceed those values.
More cells forming north and west behind the strongest ones on the
southern end may move over areas already hard hit by the first
cells, as they too train along the same boundary.
CAMs guidance has been poor with these cells so far, but for those
that are capturing the cells, they suggest they will continue to
move a bit east of due south over the next few hours. Assuming the
storms survive to San Antonio and the I-10 corridor east of the
city, rapidly decreasing instability and much higher FFG values
will quickly diminish the flash flooding threat. With some
suggestion that the cells may turn due south, San Antonio proper
should follow the latest forecasts as the cells approach.
Wegman
...Please see www.wpc.ncep.noaa.gov for graphic product...
ATTN...WFO...EWX...SJT...
ATTN...RFC...WGRFC...NWC...
LAT...LON 31500023 31129876 30669790 30359750 29969734
29609732 29539777 29299849 29419878 29959910