MESOSCALE PRECIPITATION DISCUSSION 0043
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1023 PM EDT FRI MAY 09 2014
 
AREAS AFFECTED...SOUTHERN LA...SOUTHERN MS...SOUTWEST AL...EXTREME
WESTERN FL 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 100210Z - 100545Z
 
SUMMARY...PERSISTENT BAND OF VERY HEAVY RAIN AND THUNDERSTORMS
WILL CONTINUE THE NEXT FEW HOURS...WITH CONCERN FOR LOCALLY
SIGNIFICANT REPEATING OF CONVECTIVE CELLS FOSTERING AN ELEVATED
RISK OF FLASH FLOODING.

DISCUSSION...LATEST RADAR AND SAT TRENDS SHOW A PERSISTENT BAND OF
HEAVY RAIN WITH EMBEDDED STRONGER THUNDERSTORMS IMPACTING PORTIONS
OF SOUTHERN LA AND EXTENDING ENEWD ALL THE WAY INTO THE FAR WRN FL
PANHANDLE. THERE ARE BREAKS WITHIN THE CONVECTIVE BAND...BUT THE
LATEST IR SAT IMAGERY SHOWS SOME COOLING OF CLOUD TOPS JUST
OFFSHORE SRN LA AND OVER COASTAL AREAS OF MS AND AL WHERE INTENSE
RAINFALL AMTS HAVE ALREADY BEEN REPORTED.

A VERY HIGH AMT OF MOISTURE IN THE VERTICAL COLUMN AS PER 00Z RAOB
AT LIX WITH A PWAT OF 2.16 INCHES WILL SUPPORT INTENSE RAINFALL
RATES...AND GIVEN THE DEEP WARM NATURE OF THE COLUMN...SOME
RAINFALL RATES COULD APPROACH 3 INCHES/HR AT LEAST LOCALLY AND ESP
WITH THE COOLING OF CLOUD TOPS SEEN. THE LATEST RAP ANALYSIS SHOWS
THE BEST INSTABILITY POOLED OVER THE NORTHERN GULF OF MEXICO...BUT
THE HI-RES MODELS SUPPORT A PERSISTENT AND STEADY LOW LVL SRLY
FEED OF 20 TO 25 KTS...WHICH WITH SBCAPE VALUES JUST OFFSHORE OF
NEAR 2000 J/KG AND PWATS AOA 2 INCHES SHOULD SUPPORT A SUSTAINABLE
BAND OF CONVECTION OVER THE NEXT FEW HRS WITH CELL REDEVELOPMENT
ESP NOTED ALONG THE LEADING EDGE OF A WELL-DEFINED COLD POOL. OVER
THE COLD POOL AREA...ADDITIONAL MDT TO HVY RAINS WILL CONTINUE AND
WILL IMPACT AREAS ALREADY AFFECTED BY HVY RAINS.

THE LATEST HI-RES MODELS...INCLUDING THE 18Z NAM-CONEST...12Z
HRW-ARW AND 12Z HRW-NMM SUGGEST VERY HVY RAINFALL POTENTIAL
THROUGH 06Z...WITH ADDITIONAL RAINFALL AMOUNTS OF 3 TO 6 INCHES
POSSIBLE. GIVEN EARLY RAINS...THE THREAT FOR FLASH FLOODING IS
ELEVATED.

ORRISON

ATTN...WFO...MOB...JAN...LIX...LCH...

ATTN...RFC...LMRFC...SERFC...

LAT...LON   30868655 30268696 29838822 29468975 29299064 29209152
            29219246 29399298 29829319 30379268 30959078 31388841
            31388686 30868655