MESOSCALE PRECIPITATION DISCUSSION 0050
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
417 PM EDT SUN MAY 19 2013
 
AREAS AFFECTED...EXTREME WESTERN NC...EXTREME EASTERN
TN...SOUTHWEST VA...SOUTHERN WV...EXTREME EASTERN KY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 192015Z - 200015Z
 
SUMMARY...SLOW-MOVING AND/OR STATIONARY COLD TOPPED CONVECTION
OVER THE HIGHER TERRAIN OF THE SOUTH-CENTRAL APPALACHIANS WILL
FAVOR INTENSE RAINFALL RATES WITH RAPID RUNOFF CONDITIONS POSSIBLE.

DISCUSSION...LATEST IR/VIS SAT IMAGERY SHOWS VERY SLOW-MOVING AND
LOCALLY STATIONARY CLUSTERS OF COLD TOPPED CONVECTION OVER THE
HIGHER TERRAIN OF WRN NC AND EXTREME ERN TN...WITH AN AXIS THEN
EXPANDING NORTH INTO SWRN VA AND FAR SRN WV. CLOUD TOPS HAVE BEEN
COOLING THE LAST COUPLE OF HOURS AS DIURNAL HEATING BECOMES
MAXIMIZED. THIS COUPLED WITH OROGRAPHIC LIFT...WEAK STEERING
CURRENTS AND RELATIVELY STEEP MID LEVEL LAPSE RATES ASSOCIATED
WITH A MID LEVEL TROUGH OVER THE REGION WILL FAVOR THE CURRENT
CONVECTION AT LEAST BEING SUSTAINABLE FOR THE NEXT 3 TO 4 HOURS.
ALTHOUGH...EXPECT THE CONVECTION TO BE WANING TOWARD SUNSET AS
SFC-BASED INSTABILITY IS OVERTURNED. THE SLOW-MOVEMENT AND LOCALLY
STATIONARY MOVEMENT OF THE CONVECTIVE CELLS THE NEXT FEW HOURS
WILL BE SUPPORTIVE OF RAINFALL RATES OF 1 TO 2 INCHES/HR...BUT
OVER HIGHER TERRAIN THIS MAY LEAD TO LOCALLY INTENSE RUNOFF
PROBLEMS AND RESULT IN FLASH FLOODING...ESP IF CELLS PERSIST FOR
ONLY A COUPLE OF HOURS.

ORRISON


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

LAT...LON   35538249 35128339 35518363 35858322 36418253 37248270
            37738231 38048191 38188130 38158105 37688113 37138116
            36258160 35808212 35538249