MESOSCALE PRECIPITATION DISCUSSION 0082
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
116 PM EDT THU MAY 29 2014
 
AREAS AFFECTED...EASTERN LA AND WESTERN MS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 291716Z - 292216Z
 
SUMMARY...THUNDERSTORMS WITH HEAVY RAINFALL ARE EXPECTED TO
DEVELOP AND MOVE INTO THIS REGION OVER THE NEXT SEVERAL HOURS. 
RAINFALL RATES UP TO 2" AN HOUR IN STRONGER STORMS COULD CAUSE
REGIONAL FLASH FLOODING OVER SATURATED SOILS.

DISCUSSION...AN AREA OF HEAVY RAINFALL LIES JUST AHEAD OF A
BAROCLINIC TROUGH NEAR THE ATCHAFALAYA BASIN.  NEW ACTIVITY IS
BEGINNING TO FORM NEAR THE PEARL RIVER BASIN ASSOCIATED WITH AN
850 HPA WIND MAXIMUM AND AN OUTFLOW BOUNDARY RETURNING NORTHWARD. 
CAPES IN THE REGION REMAIN NEAR OR ABOVE 1000 J/KG, AND 0-3 KM
SHEAR REMAINS 25-30 KNOTS.  COMBINED WITH PRECIPITABLE WATER
VALUES NEAR 1.75" -- NEAR THE 90TH PERCENTILE FOR LATE MAY -- AND
THE LOWER THRESHOLD FOR THE WET MULTI-CELL ENVIRONMENT IS MET.

NOW THAT THEY HAVE A GENERAL HANDLE ON THE CONVECTION IN THE
NORTH-CENTRAL GULF OF MEXICO, THE 12Z MESOSCALE GUIDANCE HAS
SIGNIFICANTLY CONVERGED TOWARDS A SIGNAL FOR HEAVY RAINFALL THIS
AFTERNOON STRETCHING FROM SOUTHEAST LA UP THE MISSISSIPPI RIVER
ACROSS WEST-CENTRAL MS, WITH THE NORMALLY WETTER SPC WRF AND ARW
ADVERTISING LOCAL MAXIMA OF 5-7".  THIS SETUP IS REMINISCENT OF
THAT OF MAY 14 -- MPD #0057 -- THOUGH FARTHER TO THE WEST. 
REGIONAL FLASH FLOODING IS CONSIDERED POSSIBLE IN THIS REGION, AS
RAINFALL RATES IN STRONGER CELLS ARE EXPECTED TO REACH 2" AN HOUR,
WITH LOCAL RAINFALL AMOUNTS POTENTIALLY REACHING 5" OVER THE NEXT
SEVERAL HOURS.

ROTH

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

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

LAT...LON   29709205 31749165 33119109 33308982 32008942 30838925
            30118914 29588952 29188897 29008942 29278986 29548996
            29859009 29969036 29539131 29709205