MESOSCALE PRECIPITATION DISCUSSION 0540
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
425 AM EDT SUN JUL 23 2017

AREAS AFFECTED...SRN IN INTO KY

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

VALID 230824Z - 231130Z

SUMMARY...LOCALIZED FLASH FLOODING WILL REMAIN POSSIBLE OVER THE
NEXT 1-3 HOURS BUT THE THREAT APPEARS TO BE WANING ACROSS SOUTHERN
IN INTO NORTHWESTERN AND EASTERN KY. MAXIMUM ADDITIONAL RAINFALL
OF 1-3 INCHES IS EXPECTED THROUGH 12Z.

DISCUSSION...EXPERIMENTAL GOES 16 INFRARED IMAGERY SHOWED TWO
SEPARATE CLUSTERS OF COLDER CLOUD TOPS AT 08Z...ONE OVER THE IN/KY
BORDER AND THE OTHER OVER THE ERN OH/KY BORDER. WARMING HAS
GENERALLY BEEN OBSERVED WITH THE ERN CLUSTER OVER THE PAST 1-2
HOURS...HOWEVER LOCALIZED CLOUD TOP COOLING WAS NOTED OVER FAR
NORTHEASTERN KY AT 08Z...PERHAPS TIED TO FAVORABLE DIFFLUENT FLOW
ALOFT OVER THE REGION. THE WESTERN CONVECTIVE CLUSTER HAS BEEN
SLOWER TO WEAKEN WITH RECENT DUAL POL RADAR DERIVED RAIN RATES
NEAR 2 IN/HR OVER DUBOIS AND CRAWFORD COUNTIES IN SOUTHERN IN.
INSTABILITY CONTINUES TO WANE ACROSS THE REGION BUT REMAINS
SUFFICIENT TO SUSTAIN LOCALLY HEAVY RAINFALL RATES WHEN COMBINED
WITH PRECIPITABLE WATER VALUES NEAR 2 INCHES...AS PER RECENT GPS
SITE MEASUREMENTS.

CONVECTION HAS BEEN...AND WILL CONTINUE TO SINK SOUTH OVER THE
OHIO RIVER VALLEY THROUGH 12Z AS HEIGHT FALLS APPROACH FROM THE
NORTH. WESTERLY FLOW OF 25-35 KT CONTINUES TO OVERRUN NUMEROUS
WEST-EAST OUTFLOW BOUNDARIES ANALYZED FROM THE IN/KY BORDER INTO
SERN KY AT 08Z. THE THREAT FOR TRAINING STORMS WILL LINGER OVER
THE NEXT 2-4 HOURS...BUT THE INTENSITY OF RAINFALL RATES SHOULD
GRADUALLY WANE WITH TIME WITH LOWERING INSTABILITY. THIS SCENARIO
IS AGREED UPON BY RECENT RUNS OF THE ESRL EXPERIMENTAL HRRR WHICH
HAS BEEN HANDLING ONGOING CONVECTION THE BEST WHEN ACCOUNTING FOR
A NORTHWARD LATITUDE DISPLACEMENT COMPARED TO OBSERVATIONS.

OTTO

ATTN...WFO...ILN...IND...JKL...LMK...PAH...RLX...

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

LAT...LON   38558639 38548556 38428392 38228284 37938253
            37518260 37208350 37188628 37308737 37758789
            38498735