MESOSCALE PRECIPITATION DISCUSSION 0691
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
953 AM EST THU DEC 24 2015
 
AREAS AFFECTED...PORTIONS OF THE SOUTHEAST 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 241452Z - 241945Z
 
SUMMARY...CONTINUED TRAINING AXES OF HEAVY RAINFALL WILL LINGER
INTO THE EARLY AFTERNOON HOURS...EXTENDING FROM THE CNTRL GULF
COAST INTO THE SRN APPALACHIANS. GIVEN PRIOR RAINFALL ACROSS THE
REGION...FLASH FLOODING IS LIKELY.

DISCUSSION...MORNING ANALYSIS SHOWED A ROBUST AXIS OF PRECIPITABLE
WATER EXTENDING FROM THE CNTRL GULF OF MEXICO ACROSS THE SOUTHEAST
TO THE MID-ATLANTIC REGION. WHILE THE GREATEST MOISTURE ANOMALIES
ARE NORTH OF THE MPD THREAT AREA INTO THE MID-ATLANTIC
REGION...STANDARD DEVIATIONS OF +2 TO +3 ARE PRESENT FARTHER
SOUTH...REACHING THE GULF COAST. REGIONAL VAD WIND PLOTS AND RAP
FORECASTS INDICATE ONGOING 850-700 MB FLOW OF 35-50 KTS WILL
PERSIST OVER THE NEXT 4-5 HOURS...ALIGNED WITH THE MOISTURE PLUME
CONTINUING STRONG MOISTURE FLUX FROM THE SOUTH. 

OVER THE NEXT COUPLE OF HOURS...THERE WILL BE THE POTENTIAL AID OF
ENHANCED UPPER DIVERGENCE REACHING THE GULF COAST...OUT AHEAD OF
AN APPROACHING UPPER LEVEL SHORTWAVE NOTED IN THE CNTRL GULF OF
MEXICO AT 14Z. RECENT RUNS OF THE HRRR AND EXPERIMENTAL HRRR SEEM
TO BE HANDLING CONVECTIVE TRENDS THE BEST OF THE CONVECTION
ALLOWING MODELS...AND INDICATE THAT ONGOING TRAINING OF NARROW
AXES OF RAINFALL RATES OF 1-3 IN/HR WILL GRADUALLY DIMINISH OVER
THE NEXT FEW HOURS ACROSS NORTHERN AREAS WITH THE FOCUS OF
HEAVIEST RAINFALL SHIFTING SWWD TOWARD THE GULF COAST.
HOWEVER...GIVEN HEAVY RAINFALL ACROSS THE ENTIRE REGION OVER THE
PAST SEVERAL DAYS AND LOW FFG...FLASH FLOODING APPEARS LIKELY FROM
THE GULF COAST TO THE SRN APPALACHIANS THROUGH 18Z.

OTTO

ATTN...WFO...BMX...CAE...FFC...GSP...LIX...MOB...MRX...TAE...

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

LAT...LON   35448357 35358281 35108237 34458221 33028312 
            31378538 30288734 30368889 31148854 32958641 
            34818516