686
AWUS01 KWNH 112043
FFGMPD
ALZ000-MSZ000-LAZ000-120215-
MESOSCALE PRECIPITATION DISCUSSION 0170
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
443 PM EDT MON MAY 11 2026
AREAS AFFECTED...SOUTHERN LA INTO SOUTHERN MS/SOUTHWESTERN AL
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 112041Z - 120215Z
SUMMARY...SCATTERED THUNDERSTORMS WILL POSE A FLASH FLOOD THREAT
FROM SOUTHWESTERN LA INTO SOUTHERN MS AND FAR SOUTHWESTERN LA.
HOURLY RAINFALL OF 2 TO 3+ INCHES AND LOCALIZED TOTALS OF 3 TO 5+
INCHES ARE EXPECTED.
DISCUSSION...RADAR IMAGERY ACROSS SOUTHERN LA AT 2030Z SHOWED SLOW
MOVING THUNDERSTORMS STRETCHING FROM NEAR A SURFACE LOW (SOUTHEAST
OF LCH) INTO SOUTHERN MS/AL (JUST SOUTH OF A HZR TO PIB LINE),
NEAR A SLOW MOVING COLD FRONT. WATER VAPOR IMAGERY SHOWED A WELL
DEFINED SHORTWAVE ADVANCING EAST FROM EASTERN TX, PROVIDING ASCENT
ACROSS SOUTHERN LA. 20Z SPC MESOANALYSIS DATA SHOWED THE REGION
CONTAINED 500 TO 1500 J/KG MLCAPE AND ANOMALOUSLY HIGH PWS AT 1.6
TO 2.0 INCHES (1-2 STANDARD DEVIATIONS ABOVE THE MEAN FOR
MID-MAY).
THUNDERSTORMS ARE LIKELY TO CONTINUE EXPANDING ALONG THE FRONT AND
NEAR THE SURFACE LOW WITH A GENERAL EASTWARD TRANSLATION TO
CONVECTION WITH TIME. IN ADDITION, THINNING CLOUD COVER IN THE
VICINITY AND SOUTH OF LAKE PONTCHARTRAIN MAY ALLOW FOR LOCALLY
INCREASED INSTABILITY AND POTENTIAL FOR THUNDERSTORMS INTO THE
EARLY EVENING. EFFECTIVE BULK SHEAR RANGED FROM <20 TO >40 KT
ACROSS THE REGION AND COUPLED WITH THE MODEST INSTABILITY IN
PLACE, CELL ORGANIZATION SHOULD BE MIXED, BUT WIDESPREAD
ORGANIZATION IS NOT EXPECTED.
TWO BIG FACTORS FOR FLASH FLOODING THROUGH THE REMAINDER OF THE
AFTERNOON INTO THE EVENING HOURS WILL BE SLOW CELL MOTIONS (0-6 KM
MEAN LAYER WINDS ARE <10 KT) AND WET ANTECEDENT CONDITIONS. GIVEN
LARGE PORTIONS OF THE CENTRAL GULF COAST TO LOCATIONS 100 MILES
INLAND HAVE RECEIVED 300 TO 600 PERCENT OF THEIR AVERAGE RAINFALL
OVER THE PAST WEEK, INCREASED SOIL MOISTURE WILL BE MORE PRONE TO
RUNOFF AND FLASH FLOODING.
OTTO
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...JAN...LCH...LIX...MOB...
ATTN...RFC...ALR...ORN...NWC...
LAT...LON 31648790 31258761 30838770 30338797 29668956
29549070 29459270 29729335 30229355 30719323
31029203 31309087 31528911
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