MESOSCALE PRECIPITATION DISCUSSION 0657
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
250 PM EST WED NOV 18 2015
 
AREAS AFFECTED...WRN FL PANHANDLE INTO ERN AL/WRN GA AND ERN TN 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 181949Z - 190100Z
 
SUMMARY...FLASH FLOODING IS POSSIBLE LATER THIS AFTERNOON/EVENING
FROM THE WRN FLORIDA PANHANDLE INTO THE SRN APPALACHIANS. THE
GREATEST THREAT APPEARS TO BE ACROSS THE NRN HALF OF THE MPD
THREAT AREA WHERE 3 HRLY RAINFALL RATES OF 2-3 INCHES ARE EXPECTED.

DISCUSSION...19Z OBSERVATIONS PLACED AN OCCLUDED/COLD FRONT
THROUGH CNTRL TENNESSEE INTO W-CNTRL ALABAMA. A WARM FRONT
EXTENDED EWD FROM THE TRIPLE POINT...LOCATED IN NRN ALABAMA...INTO
CNTRL GEORGIA. VISIBLE SATELLITE OVER THE PAST 2 HOURS HAS SHOWN
BREAKS IN CLOUD COVER AND CUMULUS DEVELOPMENT OVER SRN GEORGIA AS
THE WARM FRONT LIFTS NORTH...AN INDICATION OF INCREASING
INSTABILITY OVER THE REGION. ALTHOUGH CAPE IS FORECAST TO REMAIN
LOW...THE LATEST SHORT TERM FORECASTS FROM THE RAP/HRRR ARE
INDICATING NEAR 500 J/KG IN THE VICINITY OF THE WARM FRONT BETWEEN
21Z - 00Z. 

JUST AHEAD OF THE OCCLUDED/COLD FRONT...LOW LEVEL SLY FLOW REMAINS
40 TO 60 KTS FROM THE SOUTH...STRONGER ACROSS NRN LOCATIONS. AS
THE COLD FRONT CONTINUES EWD THIS AFTERNOON/EVENING...THE CORE OF
THE STRONGEST LOW LEVEL FLOW WILL LIFT NORTH...BUT SHOULD IMPACT
THE SRN APPALACHIANS STARTING BETWEEN 21-00Z. THIS WILL OCCUR AS
BETTER MID-LEVEL HEIGHT FALLS LIFT TOWARD HIGHER
LATITUDES...HOWEVER...STRONG UPPER DIFFLUENCE WILL REMAIN OVER THE
REGION...WITH PERHAPS LOCAL ENHANCEMENT OF DIFFLUENCE OVER NRN
GEORGIA AS A VORTICITY MAX LOCATED IN THE BASE OF THE UPPER TROUGH
OVER NRN LOUISIANA SHIFTS EAST. THESE FACTORS COULD ALLOW FOR 3
HOUR RAINFALL RATES OF 2-3 INCHES AS INDICATED BY A CONSENSUS OF
THE LATEST CAM GUIDANCE.

FARTHER SOUTH ACROSS THE FLORIDA PANHANDLE AND SERN
ALABAMA...TRAINING PRE-FRONTAL LINES OF CONVECTION AND THE
APPROACH OF THE MAIN FRONTAL SQUALL LINE...MAY ALLOW FOR LOCALLY
HIGHER RAINFALL RATES GIVEN BETTER ACCESS TO INSTABILITY. ACROSS
THESE SRN LOCATIONS...WHILE LIKELY TO REMAIN ISOLATED...A FEW
LOCATIONS MAY EXPERIENCE FLASH FLOOD CONCERNS. 

OTTO

ATTN...WFO...BMX...FFC...GSP...HUN...MOB...MRX...TAE...

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

LAT...LON   35778323 35578267 34858262 33998328 33168394 
            31618460 30498534 29998608 30058739 30888728 
            31838685 33248629 34928574 35578527 35718475 
            35718439