MESOSCALE PRECIPITATION DISCUSSION 0351
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1050 AM EDT TUE JUL 14 2015
 
AREAS AFFECTED...OH, SOUTHWEST NY, WESTERN PA, NORTHWEST WV 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 141449Z - 142049Z
 
SUMMARY...TRAINING CONVECTION CAPABLE OF HOURLY RAIN RATES UP TO
2" AN HOUR COULD CAUSE FLASH FLOODING OVER SATURATED SOILS THIS
AFTERNOON.

DISCUSSION...A PAIR OF WEAK WARM FRONTS IN ASSOCIATION WITH AN
OCCLUDED LOW CENTERED NORTHWEST OF BAD AXE MI ARE EXPECTED TO BE
THE MAIN PLAYERS FOR CONVECTION TODAY.  COOLING TEMPERATURES ALOFT
ALONG WITH DEVELOPING INSTABILITY DUE TO DAYTIME HEATING AND
DECREASING CIN SHOULD SET THE STAGE FOR INCREASED THUNDERSTORM
DEVELOPMENT FROM 16Z ONWARD.  A FEW SHOWERS HAVE BEGUN TO POP UP
NEAR THE IN/OH BORDER NEAR THE SYSTEM'S COLD FRONT.  MLCAPES IN
THE REGION CURRENTLY EXCEED 1000 J/KG, AND SHOULD CONTINUE
BUILDING INTO THE AFTERNOON.  INFLOW AT 850 HPA IS 30-35 KTS, NEAR
THE MAGNITUDE OF THE 850-400 HPA MEAN WIND, WHICH SHOULD ALLOW FOR
PRECIPITATION EFFICIENCY.  PRECIPITABLE WATER VALUES OF 1.5-1.6"
EXIST HERE PER GPS INFORMATION, 1.5-2 SIGMAS ABOVE THE MEAN FOR
MID-JULY.

AS IS USUALLY THE CASE IN THIS REGION, SMALL TRAINING CONVECTIVE
LINE SEGMENTS ARE THE MAIN THREAT FROM A FLASH FLOOD PERSPECTIVE. 
ORGANIZED CONVECTION SHOULD MOVE EAST TO SOUTHEAST AT 35 KTS, WITH
ISSUES SPREADING FROM NORTHWEST TO SOUTHEAST WITH TIME WITHIN A
CONVERGENT AREA AT 850 HPA.  AREAS WITHIN WESTERN NY LOOK MOST
PRONE TO ISSUES PRIOR TO 19Z BEFORE 850 HPA INFLOW WEAKENS.  THE
AVAILABLE MOISTURE SUPPORTS RAINFALL RATES UP TO 2" AN HOUR.  THE
MESOSCALE QPF GUIDANCE SHOWS A MODEST SIGNAL FOR LOCAL AMOUNTS IN
THE 2-3" RANGE, WHICH COULD FALL QUICKLY.  FLASH FLOOD GUIDANCE
VALUES ARE QUITE LOW DUE TO RECENT RAINS, CLOSE TO 1.5" IN THREE
HOURS.  CONSIDERING SATURATED SOILS AND EXPECTED AREAL COVERAGE OF
HIGHER PRECIPITATION AMOUNTS, FLASH FLOODING IS CONSIDERED
POSSIBLE WHERE CELLS TRAIN.

ROTH

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

ATTN...RFC...MARFC...NERFC...OHRFC...

LAT...LON   43077808 43037708 42327682 41887766 41417902 
            41087936 40127911 38578111 38498251 38778329 
            39188405 39878483 40608537 41098568 41188376 
            41578176 42467988 42707933 42817913