MESOSCALE PRECIPITATION DISCUSSION 0155
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
156 PM EDT WED JUL 10 2013
 
AREAS AFFECTED...CENTRAL AND NORTHERN OH...WESTERN PA...FAR
NORTHERN WV 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 101755Z - 102355Z
 
SUMMARY...ORGANIZING COLD-TOPPED CONVECTIVE LINE OVER NRN IN AND
NWRN OH LIKELY TO STRENGTHEN AND CROSS MUCH OF CNTRL/NRN OH
THROUGH THE AFTERNOON. VERY WET ANTECEDENT CONDITIONS WILL SUPPORT
SHORT-TERM FLASH FLOOD CONCERNS AS THE LINE CROSSES.

DISCUSSION...LATEST IR SAT IMAGERY SHOWS COOLING CLOUD TOPS ASSOCD
WITH AN ORGANIZING CONVECTIVE LINE FROM N CNTRL IN INTO EXTREME
NWRN OH. ADDITIONAL SMALLER SCALE CONVECTIVE CELLS WERE SEEN
DEVELOPING FARTHER EAST OVER NRN OH. STRONG DIURNAL HEATING
THROUGH THE MORNING AND EARLY AFTERNOON HAS CONTRIBUTED TO 4500 TO
5000 J/KG OF SBCAPE...AND LATEST VIS IS INDICATING AN INCREASINGLY
AGITATED CU FIELD ALREADY OVER MUCH OF CNTRL AND NRN OH. THE
UPSTREAM CONVECTIVE LINE IS LIKELY TO STRENGTHEN FURTHER AS IT
ADVANCES EASTWARD INTO THIS STRONGLY UNSTABLE THERMODYNAMIC
ENVIRONMENT. COMPLIMENTING THIS IS THE EXPECTING FORCING ASSOCD
WITH AN ARRIVING SHORTWAVE TROUGH WHICH SHOULD PROVIDE MORE THAN
ENOUGH ASCENT FOR A SUSTAINABLE MCS TO EVOLVE THROUGH THE
AFTERNOON. EXPECTING THIS SYS TO CROSS MUCH OF CNTRL/NRN OH THIS
AFTERNOON AND POTENTIALLY MERGING WITH CELLS OUT AHEAD OF
IT...WITH THE SYS ULTIMATELY CROSSING FAR NRN WV AND GETTING INTO
WRN PA BY LATE AFTERNOON OR EARLY EVENING. ALREADY MUCH OF THE
UPPER OH VALLEY REGION HAS SEEN VERY HEAVY RAINFALL OVER THE LAST
24 HOURS...AND WITH PWATS NEAR 2 INCHES AND NEARLY SATURATED
SOILS...THE EXPECTED CONVECTION THROUGH THE AFTERNOON WILL PROMOTE
ADDITIONAL SHORT-TERM FLASH FLOOD CONCERNS. RAINFALL RATES OF 2 TO
3 INCHES/HR ARE LIKELY...BUT COULD BE HEAVIER INVOF OF CELL
MERGERS AND THUS ENHANCING THE FLASH FLOOD THREAT.

ORRISON

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

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

LAT...LON   39917963 39628053 39528160 39598278 39688346 39988450
            40488475 40968444 41558352 41578218 41908084 41748006
            40967933 39917963