MESOSCALE PRECIPITATION DISCUSSION 0027
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
220 AM EDT THU MAY 02 2013
 
AREAS AFFECTED...SOUTHERN MS...SOUTHERN AL...EXTREME WESTERN FL
PANHANDLE 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 020619Z - 020949Z
 
SUMMARY...LITTLE CHANGE IN THE OVERALL ATMOSPHERIC SETUP APPEARS
FAVORABLE TO SUSTAIN LOCALLY VERY HEAVY RAINFALL RATES ACROSS THE
CENTRAL GULF COAST STATES OVER THE NEXT FEW HOURS...CONTINUING THE
FLASH FLOOD THREAT.

DISCUSSION...LATEST RADAR IMAGERY HAS SHOWN PERSISTENT 2+ IN/HR
RAINFALL RATES WITHIN A BAND OF TRAINING HEAVY RAINS LOCATED OVER
DAUPHIN ISLAND AND NORTHWARD TOWARD THE CITY OF MOBILE. THIS BAND
WAS OCCURRING WITHIN A NEARLY STATIONARY INFLUX OF HIGHER
MOISTURE...PWS NEAR 1.50 INCHES...ADVECTING NORTHWARD FROM THE
GULF OF MEXICO...AROUND A SLOW MOVING UPPER LOW LOCATED JUST WEST
OF LAKE PONTCHARTRAIN.

THIS GENERAL PATTERN IS EXPECTED TO REMAIN NEARLY THE SAME OVER
THE NEXT 6 HOURS WITH LITTLE MOVEMENT OF THE UPPER LOW AS FORECAST
BY SHORT TERM RAP...HRW NMM/ARW MODELS. RAINFALL REPORTS OF 5-10
INCHES ARE WIDESPREAD FROM MOBILE BAY...WESTWARD TO FAR SOUTHERN
MISSISSIPPI WHICH HAS LOWERED FLASH FLOOD GUIDANCE TO LESS THAN
0.25 IN/6 HR. 

CONVECTION...WHICH HAS RECENTLY DEVELOPED ABOUT 150 MILES SOUTH OF
MOBILE BAY PER IR IMAGERY...MAY HAVE THE EFFECT OF DISRUPTING THE
INFLUX OF MOISTURE INTO THE REGION WHICH COULD LOWER RAINFALL
RATES OVER THE NEXT FEW HOURS. HOWEVER...GIVEN SATURATED
SOILS...AND THE QUASI-STATIONARY PLACEMENT/MAGNITUDE OF 850 MB
WINDS AND MOISTURE AXIS...THE HIGHLIGHTED REGION WILL CONTINUE TO
BE AN AREA OF CONCERN WITH REGARD TO FLASH FLOODING THROUGH 10Z.
WILL RE-ASSESS THE SITUATION IN A FEW HOURS FOR CHANGES.

OTTO


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

LAT...LON   30348750 30008796 30248896 31448944 32428922 32408796
            31178730 30348750