MESOSCALE PRECIPITATION DISCUSSION 0420
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
622 PM EDT MON OCT 13 2014
 
AREAS AFFECTED...WRN FL...FAR SRN MS...SRN AL...FAR SW GA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 132221Z - 140421Z
 
SUMMARY...THE EARLY ONSET OF A POTENTIALLY LENGTHY PERIOD OF HEAVY
RAIN IS EXPECTED THIS EVENING. GIVEN RICH MOISTURE AND STRONG
INFLOW TO SUSTAIN STORMS...FLASH FLOODING MAY BE OBSERVED IN THIS
REGION BY 01-04Z.

DISCUSSION...AS OF 22Z RADAR AND SATELLITE TRENDS SUPPORTED HIGH
RESOLUTION MODELS IN SUGGESTING THAT AN ANTICIPATED HEAVY RAIN
EVENT WAS BEGINNING ALONG THE GULF COAST. THIS REGION WAS AT THE
NOSE OF A BROAD PLUME OF ENHANCED DEEP-LAYER MOISTURE AND
ASSOCIATED INSTABILITY AS DETAILED IN A RECENT NESDIS MESSAGE.
SATELLITE IMAGERY AND RAP FORECASTS INDICATED A LEAD SHORTWAVE
TROUGH APPROACHING FROM THE CENTRAL GULF...PROMOTING AN INCREASE
OF CONVECTION AHEAD OF A QUASI-LINEAR SYSTEM. WARM ADVECTION ALONG
THE EAST SIDE OF THE MOISTURE PLUME HAD LEAD TO FOCUSED STORM
CLUSTERS IN THE FLORIDA PANHANDLE. DESPITE STRONG SHEAR AND
RESULTING SUPERCELL CHARACTER IN SOME OF THE STORMS...RADAR
ESTIMATED RAIN RATES WERE STILL IMPRESSIVE AT ANYWHERE FROM 1.5 TO
JUST UNDER 2.5 INCHES IN AN HOUR.

THE LEAD SHORTWAVE...FOLLOWED BY THE APPROACH OF THE BROAD SCALE
UPPER TROUGH AND ASSOCIATED SQUALL LINE...SHOULD LEAD TO A GRADUAL
INCREASE OF AREAL COVERAGE OF HEAVY RAIN. ON A FINER SCALE...THE
12Z NSSL WRF AND SUCCESSIVE...18-20Z...HRRR RUNS SHOW A SIGNAL FOR
ESPECIALLY HEAVY RAIN THROUGH 04Z ALONG AN AXIS FROM THE FLORIDA
PANHANDLE TO SOUTHEAST ALABAMA. THIS AXIS HAD ALREADY REVEALED
ITSELF IN RADAR TRENDS...RUNNING FROM APALACHICOLA AND PANAMA CITY
NORTHWARD. THE FLASH FLOOD THREAT IS EXPECTED TO PERSIST AND
PERHAPS WORSEN LATER IN THE NIGHT... ESPECIALLY NEAR THE
COAST...AS THE UPPER PATTERN YIELDS STRONG INFLOW WITHOUT MUCH
FRONTAL PROGRESSION.

BURKE

ATTN...WFO...BMX...FFC...LIX...MOB...TAE...

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

LAT...LON   33178568 32828502 32088469 31178458 29808466 
            29048619 29588875 30598894 32198770 33048657