494
AWUS01 KWNH 041940
FFGMPD
MSZ000-LAZ000-ARZ000-TXZ000-050137-
MESOSCALE PRECIPITATION DISCUSSION 1201
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
338 PM EDT FRI SEP 04 2026
AREAS AFFECTED...IN AND NEAR LOUISIANA
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE
VALID 041937Z - 050137Z
SUMMARY...THUNDERSTORMS WITH HEAVY RAINFALL ARE REDEVELOPING NEAR
THE LA/MS BORDER. HOURLY RAIN AMOUNTS TO 3" WITH LOCAL TOTALS TO
5" COULD LEAD TO FLASH FLOODING, PARTICULARLY IN URBAN AREAS.
DISCUSSION...SHOWERS AND THUNDERSTORMS ARE REDEVELOPING NEAR THE
LA/MS BORDER, POSSIBLY CAUSED FROM AN MCV THAT MOVED OUT OF
EARLIER ACTIVITY. THE REGION IS AROUND THE NORTHERN SIDE OF A
LARGE UPPER LEVEL LOW ENCOMPASSING THE GULF. PRECIPITABLE WATER
VALUES ARE 2.25-2.5". ML CAPE IS 1500-2500 J/KG, AND CIN IS
ERODING IN AND NEAR SOUTHERN MS. EFFECTIVE BULK SHEAR IS <25 KTS,
WHICH SHOULD LEAD TO PULSE CONVECTION.
THE MESOSCALE GUIDANCE SHOWS A GENERAL UPTICK AND THEN COLLAPSE OF
CONVECTION REGIONALLY OVER THE NEXT SIX HOURS, THOUGH THE DEGREE
OF COVERAGE SHOWS SIGNIFICANT VARIANCE -- THE 12Z HREF IS MUCH
MORE BULLISH THAN THE 12Z REFS -- WHICH LEADS TO GREATER
UNCERTAINTY THAN USUAL IN CONVECTIVE EXPECTATIONS. THE RAP OPENS
UP AN 850 HPA LOW OFFSHORE SOUTHEAST LA AND MOVES A ZONE OF 850
HPA CONFLUENCE INTO SOUTHERN LA WITH TIME, WHICH COULD AID HEAVY
RAINFALL PRODUCTION. GIVEN THE PARAMETERS IN PLACE, HOURLY
AMOUNTS TO 3" WITH LOCAL TOTALS TO 5" ARE POSSIBLE WHERE CELL
MERGE OR MANAGE TO TRAIN. THIS DEGREE OF RAINFALL WOULD BE MOST
PROBLEMATIC IN URBAN AREAS. FLASH FLOODING IS POSSIBLE.
ROTH
..PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT
ATTN...WFO...HGX...JAN...LCH...LIX...MOB...SHV...
ATTN...RFC...FWR...ORN...NWC...
LAT...LON 33029349 32929046 30508913 28988912 29089138
29669489 31679506
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