447
AWUS01 KWNH 130324
FFGMPD
TXZ000-130700-
MESOSCALE PRECIPITATION DISCUSSION 0099
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1123 PM EDT SUN APR 12 2026
AREAS AFFECTED...CENTRAL TX
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY
VALID 130322Z - 130700Z
SUMMARY...A SMALL, SLOW MOVING CLUSTER OF THUNDERSTORMS IS
EXPECTED TO MAINTAIN PEAK RAINFALL RATES OF 2 TO 3+ IN/HR AND
LOCALIZED FLASH FLOODING ACROSS PORTIONS OF CENTRAL TX OVER THE
NEXT 2-4 HOURS. AFTERWARD, EASTWARD TRANSLATION AND WEAKENING IS
ANTICIPATED.
DISCUSSION...03Z RADAR IMAGERY SHOWED A SMALL THUNDERSTORM CLUSTER
OVER AND JUST WEST OF THE COLORADO RIVER IN SAN SABA AND LLANO
COUNTIES. THIS CLUSTER HAS HAD A HISTORY OF BACKBUILDING AND
TRAINING WITH OBSERVED HOURLY RAINFALL OF 2.5 INCHES AND
MRMS-DERIVED ESTIMATES LOCALLY OVER 3 INCHES OVER SAN SABA COUNTY.
IT WAS LOCATED JUST ON THE COOL SIDE OF AN ELONGATED, REMNANT
OUTFLOW BOUNDARY FROM EARLIER ON SUNDAY THAT EXTENDED FROM NEAR
NEW BRAUNFELS INTO THE HILL COUNTRY AND NORTHWARD ACROSS I-20,
JUST EAST OF ABILENE. WATER VAPOR IMAGERY SHOWED A NUMBER OF
VORTICITY MAXIMA EMBEDDED WITHIN THE WSW FLOW ALOFT. AT 03Z, A
MORE NOTABLE VORTICITY MAX WAS LOCATED JUST NORTHEAST OF SAN
ANTONIO, WITH ANOTHER MORE SUBTLE FEATURE OVER CONCHO AND MENARD
COUNTIES, WEST OF THE ONGOING THUNDERSTORMS.
EXPECTATIONS ARE FOR LOW LEVEL FLOW OVERRUNNING THE OUTFLOW TO
CONTINUE TO SUPPORT THUNDERSTORMS OVER PORTIONS OF CENTRAL TX
WITHIN A MODERATELY UNSTABLE AIRMASS CHARACTERIZED BY 1500 TO
2000+ J/KG MLCAPE AND PWS OF 1.5 TO 1.7 INCHES (SPC MESOANALYSIS).
HOWEVER, PASSAGE OF THE VORTICITY MAXIMA/SHORTWAVE FEATURES ALOFT
SHOULD CAUSE THE ONGOING ACTIVITY TO SHIFT EAST IN ANOTHER COUPLE
OF HOURS WHILE ADDITIONAL DEVELOPMENT OCCURS DOWNSTREAM TOWARD THE
EAST, WITH EVENTUAL WEAKENING AS INCREASING CIN IS ENCOUNTERED
TOWARD THE EAST. THERE IS SOME UNCERTAINTY WITH EXACTLY HOW LONG
THE BACKBUILDING SIGNATURE WILL CONTINUE OVER SAN SABA AND LLANO
COUNTIES, BUT CURRENT THINKING IS THAT THE PASSAGE OF THE EMBEDDED
IMPULSES ALOFT SHOULD DISRUPT THE ONGOING ACTIVITY WITHIN THE NEXT
2-3 HOURS.
OTTO
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...EWX...FWD...SJT...
ATTN...RFC...FWR...NWC...
LAT...LON 32069713 31929682 31659668 31359660 31129663
30859695 30689738 30599828 30679895 30929919
31089929 31379914 31579875 31879812 32039757
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