MESOSCALE PRECIPITATION DISCUSSION 0532
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
601 AM EDT SAT JUL 22 2017

AREAS AFFECTED...OH INTO FAR NWRN WV/WRN PA

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

VALID 220959Z - 221500Z

SUMMARY...RAINFALL RATES OF 1-2 IN/HR WITH PERIODS OF TRAINING
WILL POSE A FLASH FLOOD THREAT FROM PORTIONS OF CNTRL OH INTO FAR
NWRN WV/WRN PA THROUGH 15Z. 2-4 INCHES OF RAIN WILL BE POSSIBLE
FOR A FEW LOCATIONS.

DISCUSSION...0915Z REGIONAL RADAR SHOWED A WELL DEFINED MCV NEAR
THE MI/IN/OH TRI-STATE BORDER WITH A FORWARD PROPAGATING LINE
SEGMENT CROSSING I-75 NORTH OF DAY. A FEW CELLS OUT AHEAD OF THE
NRN PORTION OF THIS LINE SEGMENT HAVE ALLOWED FOR TRAINING RAIN
FROM WEST TO EAST WITH KILN RADAR ESTIMATES OF 1.5 TO 2.0 IN/HR
OVER SWRN ALLEN COUNTY FROM 09Z. RAP ANALYSES INDICATE THAT THE
MCV IS ASSOCIATED WITH A SMALL CORRIDOR OF STRONGER 850-700 MB
FLOW...30-40 KT...WHICH IS LOCALLY AIDING MOISTURE TRANSPORT FROM
THE SOUTHWEST. WHILE MUCAPE IS ESTIMATED TO BE MINIMAL ACROSS
CNTRL AND ERN OH...NEAR OR BELOW 500 J/KG...MUCAPE HAS BEEN
STEADILY INCREASING AHEAD OF THE MCV ACCORDING TO THE LATEST SPC
MESOANALYSIS PAGE.

WHILE EXPERIMENTAL GOES 16 INFRARED CLOUD TOPS HAVE GENERALLY
WARMED OVER THE PAST COUPLE OF HOURS...A REGION OF PERSISTENT
COOLING REMAINS OVER WRN OH. IN ADDITION TO BRIEF TRAINING AHEAD
OF THE MAIN LINE...THERE IS THE POTENTIAL FOR THE
INTENSIFICATION/REDEVELOPMENT OF CONVECTION BEHIND THE LEADING
CONVECTIVE LINE GIVEN A HIGHER RESERVOIR OF INSTABILITY TO THE
WEST OVER IN...AND MODERATELY STRONG WLY FLOW OF 40-50 KT. POCKETS
OF FLASH FLOOD GUIDANCE BELOW 2 INCHES IN 3 HOURS ARE IN PLACE
OVER PORTIONS OF CNTRL OH INTO FAR NWRN WV WHICH MAY BE EXCEEDED
AND LEAD TO LOCAL RUNOFF PROBLEMS. THE LATEST RUNS OF THE HRRR
SUPPORT THIS THREAT...WHEN ACCOUNTING FOR SOME LATITUDE ISSUES
NOTED WITH THE HRRR RUNS.

OTTO

ATTN...WFO...CLE...ILN...IND...IWX...PBZ...RLX...

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

LAT...LON   41258406 41078230 40938090 40588024 39848045
            39118108 39028288 39628493 40838496