MESOSCALE PRECIPITATION DISCUSSION 0048
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
954 AM EDT SUN APR 19 2015
 
AREAS AFFECTED...SOUTHEAST AL...GA...FL PANHANDLE 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 191345Z - 191800Z
 
SUMMARY...STRONG THUNDERSTORMS WITH VERY INTENSE SHORT-TERM
RAINFALL RATES OF OVER 2 INCHES/HR IS EXPECTED TO FAVOR CONCERNS
FOR FLASH FLOODING THROUGH EARLY AFTERNOON.

DISCUSSION...COOLING CONVECTIVE TOPS OVER THE NORTHERN GULF OF
MEXICO ARE MOVING INLAND ACROSS THE WESTERN FL PANHANDLE AND
SOUTHEAST AL THIS MORNING. THE ACTIVITY IS OUT AHEAD OF A
SHORTWAVE TROUGH LIFTING NORTHEAST OUT OF THE LOWER MS VALLEY.
DEEPER LAYER ASCENT/DIVERGENCE ALOFT IS COUPLING WITH CONFLUENT
LOW LEVEL FLOW AND A CHANNEL OF MODERATELY INSTABILITY FOR
CONVECTION TO CONTINUE TO ORGANIZE. IN FACT...A NOSE OF SBCAPE
VALUES OF 2000 TO 2500 J/KG AND IS NOTED AS PER LATEST RAP
ANALYSIS AHEAD OF THE CONVECTION OVER THE FL PANHANDLE AND INTO
SOUTHWEST GA...WHICH IS CONFIRMED BY THE LATEST GOES-SOUNDER DATA. 

SOUTHWEST 850MB FLOW OF 30 TO 40 KTS OVER THE REGION IS
TRANSPORTING THIS ENERGY IN OFF THE GULF OF MEXICO AND THIS WILL
CONTINUE OVER THE NEXT SEVERAL HOURS WITH A GREATER NOSE OF
INSTABILITY LIKELY EXTENDING WELL NORTHEAST INTO GA AS DIURNAL
HEATING INCREASES AND LOW LEVEL FLOW STRENGTHENS FURTHER.

ALL OF THIS SHOULD ALLOW UPSTREAM CONVECTION TO SUSTAIN ITSELF
WITH LOCALLY SOME UPTICK IN ORGANIZATION AND STRENGTH. RAINFALL
RATES ARE QUITE HIGH...EXCEEDING 2 INCHES/HR AND WITH SOME
POTENTIAL FOR BRIEFLY TRAINING CONVECTIVE SEGMENTS...SHORT-TERM
RAINFALL AMOUNTS OF 2 TO 4 INCHES AND ISOLATED HEAVIER TOTALS CAN
BE EXPECTED. THIS IS SUPPORTED BY THE 00Z GEM-REGIONAL AND THE
LATEST HRRR RUN. THIS WILL AT LEAST FOSTER A SHORT-TERM RISK FOR
FLASH FLOODING.

ORRISON

ATTN...WFO...BMX...FFC...JAX...MOB...TAE...

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

LAT...LON   33348433 33218354 32728307 31568302 30668348 
            29898410 29638469 29628526 29918577 30198650 
            30398663 30908633 31988565 33118487