MESOSCALE PRECIPITATION DISCUSSION 0210
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
318 AM EDT SAT AUG 10 2013
 
AREAS AFFECTED...WV...EASTERN KY...SOUTHWEST VA...NORTHEAST
TN...SOUTHERN OH 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 100705Z - 101205Z
 
SUMMARY...WEST TO EAST TRAINING OF CELLS WILL YIELD A THREAT OF
FLASH FLOODING THROUGH EARLY MORNING.

DISCUSSION...THIS MORNING WEAK WARM ADVECTION AND CONFLUENCE OF
WINDS IN THE 850-700 MB LAYER WAS SETTING UP OVER THE APPALACHIANS
AND EXTENDING WESTWARD THROUGH PARTS OF OH/KY/TN. THIS WAS
OCCURRING IN THE ENTRANCE REGION OF A FOCUSED 120 KT 250 MB JET.
WITH THE JET LOCATED WELL TO THE NNE...THE CONFLUENCE ZONE WAS
RATHER BROAD IN SCALE...SUGGESTING MULTIPLE WEST-EAST BANDS OF
CONVECTION MAY RESULT. ADD TO THIS THE ORGANIZING INFLUENCE OF A
SHORTWAVE TROUGH BRUSHING ACROSS THE CONFLUENCE ZONE...AND LOW
LEVEL UPSLOPE INTO THE MOUNTAINS...AND THERE IS SUPPORT FOR GENTLE
BUT PERSISTENT ASCENT IN THIS REGION...WHICH THE RAP SUSTAINS
THROUGH AT LEAST 12Z. DURING THAT TIME THE HRRR ALSO PRODUCES A
SIZEABLE SWATH OF MDT/HVY PRECIPITATION.

GIVEN THE HISTORY OF THIS SETUP OVER THE PAST FEW NIGHTS...THERE
IS SOME CONCERN FOR THE POSSIBILITY OF VERY EFFICIENT RAINFALL
RATES AND TRAINING ECHOES...WITH PW VALUES NEAR 2 INCHES AND VERY
WEAK COLD POOL FORMATION. THE CORRIDOR OF GREATEST MID LEVEL
ASCENT PER THE RAP FORECAST IS ACROSS KY/WV...AND AT 0645Z RADAR
ECHOES WERE INCREASING IN THAT CORRIDOR. WHEREVER TRAINING OCCURS
FOR MORE THAN AN HOUR...SOME LOCATIONS COULD SEE THE ROUGHLY 1.5-2
INCHES RAIN NECESSARY TO MEET FLASH FLOOD GUIDANCE IN THIS REGION.

BURKE

ATTN...WFO...RNK...RLX...GSP...MRX...JKL...ILN...LMK...

ATTN...RFC...LMRFC...MARFC...OHRFC...SERFC...

LAT...LON   38058019 37508025 36478086 36058182 36028314 36238430
            36608474 37978538 38708445 38998120 38558026 38058019