MESOSCALE PRECIPITATION DISCUSSION 0781
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1109 PM EDT MON SEP 04 2017

AREAS AFFECTED...OH/WESTERN PA

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

VALID 050310Z - 050610Z

SUMMARY...SHORT TERM TRAINING CONVECTION ALONG AND AHEAD OF A COLD
FRONT STRETCHING FROM ONTARIO INTO OH/IN COULD PRODUCE HOURLY
RAINFALL RATES NEAR 2.00 INCHES. THESE RAINFALL AMOUNTS COULD
RESULT IN A SHORT TERM FLASH FLOOD THREAT INTO THE EARLY MORNING
HOURS.

DISCUSSION...REGIONAL RADARS SHOWED A LINE OF BROKEN CONVECTION
EXTENDING FROM WESTERN NY STATE ACROSS OH INTO CENTRAL IN. FOR THE
MOST PART...THE RADAR PRESENTATION OF THE CONVECTION SUGGESTS THAT
IT IS MAINLY OUTFLOW DRIVEN...WITH SOME HAIL INDICATED (BY BOTH
SPOTTER REPORTS AND HCA PRODUCTS FROM THE KILN/KCLE RADARS).

THIS PRESENTATION IS SUPPORTED BY 00Z SOUNDINGS FROM
ILX/ILN...WHICH SHOWED STEEP MID LEVEL LAPSE RATES (GREATER THAN
7.0 C/KM) AND DRY AIR IN THE MID LEVELS. HOWEVER...AS PROPAGATION
VECTORS SLOW FOR A TIME ACROSS PORTIONS OF OH INTO WESTERN
PA...THE POTENTIAL FOR SHORT TERM TRAINING EXISTS. WHERE SHORT
TERM TRAINING OCCURS (LIKE WESTERN/CENTRAL OH)...HOURLY RAINFALL
RATES COULD APPROACH 2.00 INCHES (AS SEEN ON THE KILN/KCLE RADARS
IN THE PAST HOUR). THESE AMOUNT ARE SUPPORT BY SPOTTER REPORTS OF
1.50/2.00 INCHES OVER CENTRAL OH.

WHILE ONE AND THREE HOUR FLASH FLOOD GUIDANCE VALUES ARE GENERALLY
ABOVE 2.00 INCHES...A SHORT FUSED FLASH FLOOD THREAT IS EXPECTED
INTO THE EARLY MORNING HOURS. MOST OF THE HIGH RESOLUTION GUIDANCE
(INCLUDING THE MOST RECENT HRRR) INDICATED LOCAL 2.00 INCH
RAINFALL AMOUNTS THROUGH ABOUT 05/06Z ACROSS PORTIONS OF OH.

HAYES

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

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

LAT...LON   41998045 41607943 40937921 40377991 40367993
            40268037 39668367 39458531 39978557 40538522
            40808461 41838198