MESOSCALE PRECIPITATION DISCUSSION 0026
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
754 PM EDT WED MAY 01 2013
 
AREAS AFFECTED...SOUTHERN MS...SOUTHERN AL...EXTREME WESTERN FL
PANHANDLE 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 012354Z - 020554Z
 
SUMMARY...VERY HEAVY RAINFALL FROM VERY SLOW-MOVING AND MERGING
CONVECTION IS EXPECTED TO RESULT IN AN ELEVATED FLASH FLOOD THREAT
THROUGH THE EVENING ALONG PORTIONS OF THE CENTRAL GULF COAST.

DISCUSSION...RADAR IMAGERY INDICATES A WELL-DEFINED MESOCYCLONE
HAS DEVELOPED OVER FAR SOUTHERN MS OVER THE LAST COUPLE OF
HOURS...WHICH IS AIDING THE PERSISTENCE OF AN INTENSE BAND OF
CONVECTION FROM JUST SOUTH OF GULFPORT MS NORTHEAST TO AREAS JUST
NORTHWEST OF MOBILE AL. IR SATELLITE IMAGERY SHOWS SUSTAINABLE
COLD CONVECTIVE CLOUD TOPS WITH OCCASIONAL OVERSHOOTING TOP
DETECTIONS ACROSS THIS AREA. THE CONVECTION CONTINUES TO BE AIDED
BY A FEED OF VERY MOIST AND UNSTABLE LOW LEVEL FLOW IN OFF THE
NORTHEAST GULF OF MEXICO. A LOW LEVEL JET ON THE ORDER OF 30 TO 40
KTS IS EXPECTED TO CONTINUE THROUGH THE EVENING HOURS HERE...WHICH
IS SUPPORTED BY THE 12Z ECMWF. 

THE 18Z NAM-CONEST AND 12Z HRW-ARW BOTH HAVE CAPTURED RELATIVELY
WELL THE DETAILS OF THE MCV...AND ONGOING CONVECTION...AND SUGGEST
A GRADUAL EASTWARD PIVOT TO THIS VORT CENTER ALONG WITH A
WELL-CONCENTRATED AND ORGANIZED CONVECTIVE BAND. THE BAND WILL BE
CAPABLE OF PRODUCING VERY HEAVY RAINFALL AMTS...AND ESP SINCE
THERE HAVE BEEN NUMEROUS CONVECTIVE ELEMENTS ADVANCING
NORTHWESTWARD IN OFF THE GULF OF MEXICO AND MERGING IN WITH THE
LARGER SCALE BAND. RAINFALL RATES OF 2 TO 3 IN/HR WILL BE EXPECTED
LOCALLY. RAINFALL AMTS THROUGH THIS TIME PERIOD ALONE OF 3 TO 6
INCHES WITH ISOLATED HEAVIER AMTS ARE EXPECTED. 

IT SHOULD BE NOTED THAT THE 18Z NAM-CONEST AND 12Z HRW-ARW...ALONG
WITH THE 12Z ECMWF HIGHLY SUGGEST THIS EVENT WILL CONTINUE WELL
AFTER MIDNIGHT WITH A HIGH-IMPACT AND POTENTIALLY LIFE-THREATENING
FLASH FLOOD EVENT BEING SUGGESTED. WILL CONTINUE TO MONITOR.

ORRISON


ATTN...WFO...BMX...MOB...JAN...LIX...

LAT...LON   30348920 30838900 31848879 32078808 31818741 31258703
            30288704 30158811 29938880 30028923 30348920