MESOSCALE PRECIPITATION DISCUSSION 0275
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
555 PM EDT SAT MAY 27 2017

AREAS AFFECTED...EASTERN MO...SOUTHERN IL...WESTERN KY

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 272153Z - 280200Z

SUMMARY...STRONG THUNDERSTORMS FROM EASTERN MO ACROSS SOUTHERN IL
INTO KY WILL CONTINUE THE THREAT OF FLASH FLOODING FOR THE NEXT
SEVERAL HOURS.

DISCUSSION...STRONG THUNDERSTORMS EXTENDING FROM EASTERN MO INTO
KY ARE PRODUCING LOCAL HOURLY RAINFALL RATES OF 1-1.5". THE STORMS
ARE DEVELOPING IN THE VERY MOIST AIR MASS ALONG AND JUST TO THE
SOUTH SIDE OF THE WEAK FRONTAL BOUNDARY THAT EXTENDS WEST-EAST
ACROSS THE AREA. THESE STORMS SHOULD CONTINUE FOR THE NEXT SEVERAL
HOURS...CONTINUING TO MOVE EASTWARD.

SURFACE DEW POINTS ALONG THE SOUTH SIDE OF THE FRONTAL BOUNDARY
ARE MAINLY 70 DEGREES F AND HIGHER...WITH PRECIPITABLE WATER
VALUES 1.4-1.7". SPC MESOANALYSES SHOW THE MUCAPE VALUES IN THE
RANGE OF 2500-4000 J/KG. EFFECTIVE BULK SHEAR OF 30-40 KT ACROSS
THE REGION SHOULD HELP MAINTAIN THE ORGANIZATION OF THESE STORMS.

3-HOUR FLASH FLOOD GUIDANCE VALUES ACROSS THE REGION OF CONCERN
ARE MAINLY 2-3". THE WEST-EAST TRACK OF THE STORMS MEANS THAT 
SOME AREAS WILL RECEIVE TRAINING STORMS DURING THE NEXT SEVERAL
HOURS. THE LAST FEW RUNS OF THE HRRR...WHICH SEEMS TO HAVE THE
BEST HANDLE ON THE CONVECTION AMONG THE HIRES MODELS...SUGGEST
THAT 2-3" OF RAIN WILL FALL OVER PARTS OF THE THREAT AREA WITH
LOCAL TOTALS AROUND 4". SO THE THREAT OF FLASH FLOODING WILL
CONTINUE FOR THE NEXT SEVERAL HOURS. 

MCDONNAL

ATTN...WFO...ILX...IND...JKL...LMK...LSX...OHX...PAH...SGF...

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

LAT...LON   38748984 38668718 38348536 37478400 36868369
            36588648 36769054 37089181 37119187 37769219
            38719179