MESOSCALE PRECIPITATION DISCUSSION 0195
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1003 PM EDT TUE MAY 10 2016
 
AREAS AFFECTED...PORTIONS OF TN/KY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 110202Z - 110802Z
 
SUMMARY...THUNDERSTORMS ARE EXPECTED TO BECOME MORE CONCENTRATED
AND MORE EFFECTIVELY TRAIN OVER THE NEXT SEVERAL HOURS.  HOURLY
RAIN RATES UP TO 1.75" COULD LEAD TO FLASH FLOODING.

DISCUSSION...CONVECTION WITH HINTS OF BACKBUILDING COOLING CLOUD
TOPS ACROSS KY/NORTHERN TN HAS BEEN AIDED BY SIGNIFICANT
DIVERGENCE ALOFT PARTIALLY SPONSORED BY AN MCV MOVING ACROSS
NORTHERN IN.  PRECIPITABLE WATER VALUES ARE NEAR 1.3" PER GPS
VALUES.  THE DEEP LAYER FLOW IS FAIRLY UNIDIRECTIONAL OUT OF THE
SOUTHWEST TO WEST-SOUTHWEST, WHICH RAISES THE SPECTER OF CELL
TRAINING.  MUCAPES ARE SIGNIFICANT SOUTH OF AN EFFECTIVE FRONTAL
BOUNDARY IN KY, RANGING FROM 1000-3000 J/KG.  PER THE INSTABILITY
PROFILE, CONVECTION IN SOUTHWEST KY WAS RATHER CLOSE TO THE
THERMAL GRADIENT, WHILE MORE TO THE EAST IT WAS MORE ELEVATED IN A
REGION WHERE CIN HAS TAKEN HOLD.  INFLOW AT 850 HPA IS SOUTHWEST
AT 25-35 KTS.

THE EXPECTATION IS FOR CELL TRAINING TO BECOME MORE EFFECTIVE AS
CELL COVERAGE INCREASES OVER THE NEXT SEVERAL HOURS, WITH THE DEW
POINT BOUNDARY TO THE SOUTH BECOMING THE MORE SIGNIFICANT PLAYER
IN CONVECTIVE DEVELOPMENT WITH TIME.  PRECIPITABLE WATER VALUES
ARE ALSO EXPECTED TO RISE ABOVE 1.50" WHILE LOW-LEVEL INFLOW
REMAINS RELATIVELY STATIC IN MAGNITUDE, WITH SLIGHT VEERING WITH
TIME EXPECTED PER RAP RUNS.  THE 18Z SSEO NEIGHBORHOOD
PROBABILITIES SUGGEST THAT BROADER SCALE ISSUES INCREASE BEYOND
04Z, MAXIMIZING BETWEEN 07-10Z.  HOURLY RAIN RATES OF UP TO 1.75"
ARE POSSIBLE GIVEN THE AVAILABLE MOISTURE.  THE MESOSCALE/CAM
GUIDANCE IS IN GENERAL AGREEMENT THAT LOCAL 3-5" TOTALS ARE
EXPECTED, THOUGH SOME OF THE HIGHER BIASED GUIDANCE SUPPORTS
AMOUNTS UP TO 8".  THE PLACEMENT OF THE 12Z SPC WRF, 12Z WRF 4
NSSL, 18Z NAM CONEST, 23Z EXPERIMENTAL HRRR, AND 00Z HRRR APPEARS
BEST.  ONCE ORGANIZED,  THE HIGHER RAIN CORES SHOULD MOVE
EAST-SOUTHEAST AT 20-25 KTS.  THESE SORT OF RAIN RATES/TOTALS
WOULD CAUSE FLASH FLOODING.

ROTH

ATTN...WFO...HUN...JKL...LMK...MEG...MRX...OHX...PAH...

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

LAT...LON   37798604 37338382 36218372 35228506 35068646 
            35378736 35808815 36538956 37358847