717
AWUS01 KWNH 121619
FFGMPD
TXZ000-122217-
MESOSCALE PRECIPITATION DISCUSSION 0096
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1218 PM EDT SUN APR 12 2026
AREAS AFFECTED...SOUTH-CENTRAL TEXAS
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 121617Z - 122217Z
SUMMARY...INCREASING POTENTIAL FOR FLASH FLOODING THIS AFTERNOON
AS THUNDERSTORMS CONTAINING 2-3"/HR RAINFALL RATES DEVELOP IN THE
NEXT 2-3 HOURS AND CONGEAL INTO AN MCS. LOCALLY SIGNIFICANT FLASH
FLOODING IS POSSIBLE, ESPECIALLY ATOP SENSITIVE URBAN AREAS IN THE
REGION.
DISCUSSION...SHOWERS AND THUNDERSTORMS ARE SHOWING INCREASED
DEVELOPMENT ACROSS SOUTH-CENTRAL TEXAS LATE THIS MORNING AS A VERY
MOIST AIRMASS CONTINUES TO DESTABILIZE. AN INTENSE, LOCALIZED
CLUSTER OF THUNDERSTORMS NEAR GONZALES COUNTY RECENTLY EXHIBITED
2.5-3"/HR RAINFALL RATES ACCORDING TO MRMS AND KEWX. WHEN COMBINED
WITH SLOW FORWARD MOTIONS AROUND 20 KTS, A CORRIDOR OF FFG
EXCEEDANCE WAS NOTED OVER THE LAST 15 MINUTES.
THESE EARLY STORMS ARE TAPPING INTO A VERY FAVORABLE ENVIRONMENT
FOR EFFICIENT HEAVY RAINFALL PRODUCTION; 12Z RAOB FROM BRO AND
ACARS PROFILES FROM AUS AND SAT DEPICT A DEEP MOIST LAYER FROM THE
SURFACE TO 750 MB (PWAT OF 1.7-1.8"), TALL INSTABILITY PROFILES
CHARACTERIZED BY 1000-2000 J/KG OF MUCAPE, AND WBZ HEIGHTS OVER
3500 M. AN INVERSION ABOVE THE MOIST LAYER HAS THUS FAR SUPPRESSED
MORE WIDESPREAD DEVELOPMENT, ALTHOUGH THIS IS EXPECTED TO WEAKEN
OVER TIME AS LARGE SCALE ASCENT STRENGTHENS OVER THE NEXT FEW
HOURS WHILE THE COLUMN CONTINUES TO MOISTEN.
AS SUCH, THUNDERSTORMS ARE EXPECTED TO EXPAND IN COVERAGE AND
INTENSITY OVER THE NEXT FEW HOURS. BY 17-18Z, THE 12Z CAM SUITE IS
IN GOOD AGREEMENT FOR THIS ACTIVITY TO CONGEAL INTO AN MCS
CONTAINING TRAINING THUNDERSTORMS ALONG A NE-SW AXIS -- POSSIBLY
ALONG A REMNANT COLD POOL EVIDENT IN SURFACE OBS. FORECAST CORFIDI
VECTORS NEAR 10 KTS SUGGEST THIS COMPLEX WILL BE QUITE SLOW TO
MOVE ONCE IT DEVELOPS, IN TURN LENGTHENING THE RESIDENCE TIME OF
2-3"/HR RAINFALL RATES WITHIN THE STRONGEST INDIVIDUAL CELLS.
WHILE THE AREA HAS BEEN DRY ACCORDING TO NASA SPORT SOIL MOISTURE
PERCENTILES, THE RISK OF FLASH FLOODING IS EXPECTED TO INCREASE
OVER THE NEXT 6 HOURS AS 3-6" FALL IN THE MAIN AXIS OF TRAINING.
SIGNIFICANT FLASH FLOODING IS POSSIBLE SHOULD THIS FALL OVER A
SENSITIVE URBAN AREA.
ASHERMAN
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...EWX...FWD...HGX...
ATTN...RFC...FWR...NWC...
LAT...LON 31379590 30859516 29989564 29049725 28959831
29579882 30369847 31079733
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