MESOSCALE PRECIPITATION DISCUSSION 0420
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
230 PM EDT MON JUL 04 2016
 
AREAS AFFECTED...KY...WESTERN WV 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 041830Z - 042330Z
 
SUMMARY...FLASH FLOOD THREAT EXPECTED TO EXPAND ACROSS KY INTO WV
THIS AFTERNOON.

DISCUSSION...CONVECTION CONTINUES TO EXPAND ACROSS KY AHEAD OF A
SHORTWAVE AND MCV APPARENT IN RADAR IMAGERY NEAR THE IL/KY BORDER
AS OF 18Z. FORCING AND LOW LEVEL MOISTURE TRANSPORT AHEAD OF THESE
FEATURES ALONG WITH CONTINUED RIGHT ENTRANCE JET DYNAMICS SUPPORT
CONTINUED CONVECTIVE DEVELOPMENT. VISIBLE SATELLITE SHOWS ENOUGH
BREAKS IN THE CLOUD COVER TO RESULT IN INCREASING INSTABILITY. THE
OVERLAP OF THIS INCREASING INSTABILITY AND FORCING SHOULD RESULT
IN CONTINUED SCATTERED TO WIDESPREAD CONVECTIVE DEVELOPMENT ACROSS
KY INTO WV THROUGH THE AFTERNOON. GPS DERIVED PRECIPITABLE WATER
VALUES AND RAP FORECASTS SUGGEST 2"+ PRECIPITABLE WATER VALUES
WILL CONTINUE TO OVERSPREAD THE AREA AS WELL. INDIVIDUAL STORM
MOTIONS WILL CONTINUE TO BE PROGRESSIVE. HOWEVER THE SCATTERED TO
WIDESPREAD DEVELOPMENT SHOULD RESULT IN SOME TRAINING OF
CONVECTION THROUGH THE AFTERNOON HOURS AHEAD OF THE MCV. 

WE THOUGHT THE 16Z PARALLEL HRRR HAD A PRETTY GOOD HANDLE ON THE
CONVECTIVE EVOLUTION OVER THE NEXT SEVERAL HOURS. THIS WOULD
SUGGEST AN ADDITIONAL 1-3" OVER MUCH OF CENTRAL/EASTERN KY. GIVEN
THE FAVORABLE ENVIRONMENT...WOULD NOT BE SURPRISED TO SEE LOCALLY
HEAVIER AMOUNTS WHERE TRAINING IS MAXIMIZED. GIVEN THE LOWER FLASH
FLOOD GUIDANCE OVER MUCH OF THE STATE DUE TO RECENT RAINFALL AND
SATURATING SOILS...THIS AMOUNT OF RAIN WILL RESULT IN A FLASH
FLOOD THREAT. THE BREAKS IN THE CLOUDS HAVE ALSO ALLOWED FOR
EARLIER DEVELOPMENT ACROSS WESTERN WV THAN MODELED. THIS COMBINED
WITH UPSLOPE FLOW INTO THE REGION MAY RESULT IN THE FLASH FLOOD
THREAT BEGINNING EARLIER THAN MODELED. WILL KEEP THE MPD WORDING
AS FLASH FLOODING POSSIBLE...AS THE FORWARD PROGRESSION OF THE
SYSTEM RESULTS IN LOWER CONFIDENCE FOR WIDESPREAD FLASH FLOODING
THIS AFTERNOON...WITH ISOLATED TO SCATTERED FLASH FLOOD COVERAGE
APPEARING MORE LIKELY AT THIS TIME. ALTHOUGH GIVEN THE EARLY
DEVELOPMENT...AND MULTIPLE ROUNDS YET TO COME...CONTINUE TO BE
CONCERNED ABOUT A GREATER FLASH FLOOD THREAT ACROSS
CENTRAL/SOUTHERN WV AS WE HEAD INTO THE EVENING HOURS. WILL
CONTINUE TO MONITOR.

CHENARD 

ATTN...WFO...ILN...JKL...LMK...MRX...OHX...PAH...RLX...

ATTN...RFC...LMRFC...OHRFC...

LAT...LON   38878212 38518117 37638108 37418153 37148253 
            36838454 36638565 36608685 36668713 37128825 
            37668632 38108481 38608368