MESOSCALE PRECIPITATION DISCUSSION 0272
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1115 PM EDT THU JUN 25 2015
 
AREAS AFFECTED...SOUTHERN IN, EASTERN KY, WESTERN VIRGINIAS 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 260314Z - 260914Z
 
SUMMARY...THUNDERSTORMS WITH HEAVY RAINFALL ARE EXPECTED TO MOVE
EASTWARD AND PERSIST TOWARDS DAWN.  FLASH FLOODING IS CONSIDERED
POSSIBLE.

DISCUSSION...A BAND OF THUNDERSTORMS HAS FORMED ACROSS PORTIONS OF
SOUTHEAST IL AND SOUTHERN IN, DOWNSTREAM OF MIXED LAYER CAPES OF
2000-4000 J/KG.  TO THE EAST, SCATTERED SHOWERS AND THUNDERSTORMS
HAVE BEEN SEEN ACROSS SOUTHERN WV AND EASTERN KY THIS AFTERNOON,
WHICH HAVE DROPPED LOCAL AMOUNTS OF 1-2" -- THIS HAS BEGUN TO
SATURATE SOILS LOCALLY.  RAP MASS FIELDS INDICATE STABLE 850 HPA
INFLOW ACROSS SOUTHERN IL AND SOUTHERN IN, WITH INCREASING 850 HPA
CONVERGENCE ACROSS EASTERN KY BEYOND 06Z WHILE INCREASING THE
MAGNITUDE OF 850 HPA INFLOW.  THE COMBINATION OF A DIGGING
SHORTWAVE MOVING SOUTHWARD ACROSS SOUTHEAST CANADA AND OUTFLOW
BOUNDARIES/POSSIBLE MCVS FROM UPSTREAM CONVECTION ACROSS SOUTHERN
IL APPEAR TO BE THE MAIN FORCING MECHANISMS FOR ACTIVITY IN THIS
REGION, OUTSIDE OF THE NOCTURNAL LOW-LEVEL JET.  PRECIPITABLE
WATER VALUES OF 1.5-2" ARE PRESENT BASED ON RECENT RAP
ANALYSES/FORECASTS, 1.5 SIGMAS ABOVE THE NORM FOR LATE JUNE.  NO
SIGNIFICANT CAP APPEARS TO BE IN PLACE, WITH CONVECTION EXPECTED
TO FORM CONTINUE IN THE VICINITY OF A VAGUE TEMPERATURE GRADIENT.  

MOST OF THE MESOSCALE QPF GUIDANCE -- OUTSIDE RECENT HRRR AND RAP
RUNS -- ADVERTISE LOCAL AMOUNTS OF 2-3" OF RAINFALL ACROSS EASTERN
KY OVER THE NEXT SEVERAL HOURS, WITH NONE OF THE GUIDANCE HANDLING
CURRENT ACTIVITY IN SOUTHERN IN PROPERLY.  WITH HOURLY RAIN RATES
UP TO 1.5-2" ANTICIPATED, HEAVY RAINFALL COULD OCCUR QUICKLY. 
FORWARD PROPAGATION TO THE EAST-SOUTHEAST NEAR 20 KTS IS EXPECTED
TO CONTINUE -- CELL TRAINING IS THE MAIN THREAT.  THE THREE HOURLY
FLASH FLOOD GUIDANCE VALUES ACROSS EASTERN KY ARE ON PAR WITH THE
AMOUNTS SEEN IN THE MESOSCALE GUIDANCE, MAKING THIS A BORDERLINE
EVENT WITH GREATER THAN AVERAGE UNCERTAINTY.  ACROSS SOUTHERN IN,
THE FLASH FLOOD GUIDANCE VALUES ARE LOWER.  THE STRONGEST SIGNAL
IN THE 18Z SSEO NEIGHBORHOOD PROBABILITIES IS BETWEEN 08Z-11Z,
INDICATING THAT WHATEVER ORGANIZED CONVECTION FORMS OR MOVES INTO
EASTERN KY AROUND 06Z COULD PERSIST TOWARDS SUNRISE.  FLASH
FLOODING IS CONSIDERED POSSIBLE OVER SATURATING SOILS.

ROTH

ATTN...WFO...ILN...ILX...IND...JKL...LMK...MRX...PAH...RLX...
RNK...

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

LAT...LON   39188869 39028571 38218207 37548079 36878100 
            36298189 36608385 37408605