Graphic for MPD #0172

MESOSCALE PRECIPITATION DISCUSSION 0172
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
734 AM EDT SUN APR 30 2017

AREAS AFFECTED...CENTRAL/EASTERN LA...SOUTHEAST AR...SOUTHWEST MS

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 301129Z - 301529Z

SUMMARY...STRONG THUNDERSTORMS WITH INTENSE RAINFALL RATES OVER
2"/HR WILL MOVE SLOWLY EAST FOR THE NEXT FEW HOURS. SOME FLASH
FLOODING IS POSSIBLE.

DISCUSSION...A COMPLEX OF VIGOROUS THUNDERSTORMS...BRINGING RAIN
RATES LOCALLY EXCEEDING 2"/HR...CONTINUES ACROSS ACROSS
CENTRAL/EASTERN LA AND INTO SOUTHWEST AR AS A COLD FRONT MOVES
SLOWLY EAST INTO A REGION OF INTENSE INSTABILITY AND LOW LEVEL
MOISTURE TRANSPORT FROM THE WESTERN GULF OF MEXICO. DUAL POL RADAR
SHOWS LOCAL RAINFALL TOTALS OF 6-9" FROM JUST EAST OF LAKE CHARLES
NORTHEAST INTO AVOYELLES PARISH.

CONVERGENT LOW LEVEL SOUTHERLY FLOW OF 40-55 KT...BRINGING RAIN
RATES LOCALLY EXCEEDING 2"/HR...WILL CONTINUE TO FEED A VERY MOIST
AIR MASS WITH PRECIPITABLE WATER VALUES OF 1.5-2" INTO THE REGION.
THE RAP13 AND SPC ANALYSES SHOW MUCAPE VALUES OF 1000-2500 J/KG
OVER THE AREA. THE LINE HAS BEEN MOVING EASTWARD AROUND 15
KT...BUT MODELS SUGGEST IT COULD INCREASE ITS EASTWARD PROGRESSION
TO AROUND 25 KT AS THE UPPER LEVEL SHORTWAVE APPROACHES FROM THE
WEST AND THE SYSTEM MOVES INTO A REGION OF SOMEWHAT LOWER CAPE
VALUES.

HIRES MODELS INDICATE THAT RAIN RATES WILL GRADUALLY DECREASE OVER
THE NEXT SEVERAL HOURS...BUT EVEN SO ANOTHER 3 TO 5 INCHES OF RAIN
WITH ISOLATED HEAVIER AMOUNTS CAN BE EXPECTED THROUGH AROUND 16Z.
SOME OF THESE RAINS WILL FALL ON AREAS THAT RECEIVED SIGNIFICANT
RAINFALL SATURDAY AND SATURDAY NIGHT...SO THIS MAY RESULT IN
RUNOFF PROBLEMS AND POSSIBLE FLASH FLOODING.

MCDONNAL

ATTN...WFO...JAN...LCH...LIX...SHV...

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

LAT...LON   33489114 33469010 32568979 31159021 30169085
            29589153 29429230 29669314 30369327 31549254
            32759204


Last Updated: 734 AM EDT SUN APR 30 2017