MESOSCALE PRECIPITATION DISCUSSION 0452
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1057 AM EDT FRI JUL 07 2017

AREAS AFFECTED...NRN IN INTO W-CNTRL OH

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

VALID 071456Z - 071955Z

SUMMARY...TRAINING CONVECTION COULD LEAD TO FLASH FLOODING FROM
PORTIONS OF CNTRL/NRN IN INTO WRN OH THROUGH 21Z. RAIN RATES NEAR
2 IN/HR CAN BE EXPECTED WITH 3-5 INCHES POSSIBLE.

DISCUSSION...KIWX RADAR SHOWED TRAINING HEAVY RAIN THROUGH 1430Z
ACROSS NRN IN WITH NEAR 2 IN/HR RATES OBSERVED FROM 2
WUNDERGROUND.COM OBSERVING STATIONS IN ERN MARSHALL COUNTY. THE
RAINFALL AXIS IS CURRENTLY ORIENTED FROM NW TO SE...AND AN OUTFLOW
BOUNDARY WAS OBSERVED AT 1430Z JUST SOUTHWEST OF THE ONGOING HEAVY
RAINFALL AXIS. RECENT GPS MEASUREMENTS SHOW PRECIPITABLE WATER
VALUES BETWEEN 1.25 AND 1.5 INCHES OVER CNTRL AND SRN IN...BUT
HIGHER VALUES APPROACHING AND EXCEEDING 1.75 INCHES WERE LOCATED
TO THE NORTHWEST...CLOSER TO THE LEADING EDGE OF AN APPROACHING
COLD FRONT.

850-300 MB MEAN WINDS ARE WNW AT 30 KT WHICH IS NEAR THE 850-700
MB MEAN WIND SPEED AND DIRECTION. THE CONCERN FOR FLASH FLOODING
IS ALONG THE WRN EDGE OF THE ONGOING COMPLEX WITH FLOW PARALLELING
THE OUTFLOW BOUNDARY AND ALLOWING FOR PERIODS OF TRAINING GIVEN
THE UNIDIRECTIONAL FLOW. THE MOIST AND UNSTABLE ENVIRONMENT OVER
THE REGION AND CLEAR SKIES SOUTH OF THE CONVECTIVE COMPLEX SHOULD
ALLOW FOR INCREASING INSTABILITY SO CONDITIONS APPEAR FAVORABLE
FOR CONTINUED CONVECTIVE DEVELOPMENT OVER IN/OH.

OF SECONDARY CONCERN IS AN AREA STRADDLING THE CNTRL IN/OH BORDER
WHICH RECEIVED ABOUT 1.5 TO 3.0 INCHES OF RAIN OVER THE PAST 24
HOURS WHICH HAS LOCALLY LOWERED FLASH FLOOD GUIDANCE ACROSS THE
REGION. WHILE RECENT HRRR SIMULATIONS INDICATE THE LEADING EDGE OF
THE GROWING CONVECTIVE COMPLEX SHOULD BE FORWARD
PROPAGATING...LOCALIZED FLASH FLOODING WILL BE POSSIBLE OVER ERN
PORTIONS OF THE MPD THREAT AREA AS WELL GIVEN ANTECEDENT RAINFALL
AND FFG OF 1-2 INCHES IN 3 HOURS.

OTTO

ATTN...WFO...ILN...IND...IWX...LOT...

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

LAT...LON   41878684 41038513 40548398 39858379 39288434
            39028509 39518642 41028731