MESOSCALE PRECIPITATION DISCUSSION 0658
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
758 PM EST WED NOV 18 2015
 
AREAS AFFECTED...CENTRAL AND EASTERN GA...WESTERN AND SC/WESTERN
NC 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 190100Z - 190500Z
 
SUMMARY...FLASH FLOODING IS POSSIBLE ACROSS PORTIONS OF
GA...NORTHWEST SC AND FAR WESTERN NC THROUGH THE LATE EVENING
HOURS...ESPECIALLY IN AREAS OF UPSLOPE AND WHERE TRAINING OCCURS.

DISCUSSION...A LINE OF CONVECTION CROSSING GA INTO NORTHWEST SC IS
PRODUCING LOCALLY HEAVY RAINFALL...AS THE LOW TOPPED STORMS TAP
DEEP MOISTURE (IN THE FORM OF 2.00 INCH PRECIPITABLE WATER AIR) ON
A 30 TO 40 KNOT LOW LEVEL SOUTHERLY FLOW. INSTABILITY AHEAD OF THE
FRONT IS FAIRLY MEAGER (WITH MLCAPE VALUES AT OR BELOW 500
J/KG)...BUT MRMS RAINFALL RATE AND LOCAL RADAR ESTIMATES HOURLY
RATES BETWEEN 1.50 AND 2.00 INCHES...ESPECIALLY ACROSS NORTH
CENTRAL GA.

AS A STRONG SHORT WAVE APPROACHES FROM THE GULF STATES...INCREASED
SYNOPTIC SCALE ASCENT MAY BE ABLE TO PARTIALLY COMPENSATE FOR THE
GENERAL LACK OF INSTABILITY TO KEEP THE CONVECTION FIRING AHEAD OF
THE COLD FRONT AS IT APPROACHES NORTHEAST GA...NORTHWEST SC AND
FAR WESTERN NC. THE LATEST RAP INDICATED THAT THE 30 TO 40 KNOT
LOW LEVEL SOUTHERLY FLOW PERSISTS INTO THE LATE EVENING
HOURS...TRANSPORTING 1.75 TO 2.00 INCH PRECIPITABLE WATER AIR INTO
THIS REGION. 

THE 850-300 MB FLOW BECOMES BETTER ALIGNED WITH THE CORFIDI
VECTORS FOR A TIME THIS EVENING...WHICH WOULD PROMOTE THE
POTENTIAL FOR TRAINING. LOW TOPPED CONVECTION TRACKING NORTHWARD
ACROSS EAST GA AND SOUTHERN SC COULD MERGE WITH THE CONVECTION
AHEAD OF THE COLD FRONT... RESULTING IN A LOCALLY HIGHER THREAT
FOR FLASH FLOODING. 

THREE HOUR FLASH FLOOD VALUES ARE FAIRLY HIGH ACROSS THIS REGION.
THE POTENTIAL FOR TRAINING...AS WELL AS UPSLOPE FLOW GIVEN THE
STRONG LOW LEVEL SOUTHERLY FLOW... COULD RESULT IN LOCAL HOURLY
RAINFALL RATES NEAR 2 INCHES. ALMOST ALL OF THE HIGH RESOLUTION
GUIDANCE IS SLOW WITH THE CONVECTION...BUT INDICATE LOCAL 3-4 INCH
RAINFALL AMOUNTS ACROSS NORTHWEST SC AND WESTERNMOST NC THROUGH
19/05. 

HAYES

ATTN...WFO...CAE...CHS...FFC...GSP...JAX...RNK...TAE...

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

LAT...LON   36138145 36128103 35648071 34668083 34158116 
            33608152 32718201 32688202 32198229 31728258 
            30988323 30638352 30528379 30518389 30708470 
            30728453 30948475 32468465 32548460 34318374 
            35548288