MESOSCALE PRECIPITATION DISCUSSION 0440
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
924 PM EDT MON AUG 10 2015
 
AREAS AFFECTED...WESTERN NEW YORK...EASTERN PENNSYLVANIA...EXTREME
NORTHEAST OHIO 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 110122Z - 110622Z
 
SUMMARY...NARROW WINDOW IN SPACE AND TIME FOR DEEPER CONVECTION
WITH RATES IN EXCESS OF 1.5"/HR BEFORE WEAKENING INTO PROLONGED
MODERATE RAINFALL EVENT

DISCUSSION...WEAK SHORTWAVE CURRENT ANALYZED NEAR FKL IN ADVANCE
OF BASE OF STRONGER TROF BACK ACROSS THE LOWER PENINSULA OF
MI...KEEPS BACKED FLOW OVER CENTRAL PA AND NY CONTINUING TO PUMP
SOUTHERLY MOIST AND UNSTABLE AIR IN ADVANCE OF DEVELOPING SURFACE
LOW...WITH 1.6-1.7 TPWS AND 500-1500 J/KG OF CAPES PER 00Z BUF AND
PIT RAOBS.  THE INTERACTION OF THE SHORTWAVES AND DEVELOPING
SURFACE LOW WILL ACT TO GENERATE A PIVOT POINT NEAR CLE TO ERI
OVER THE NEXT FEW HOURS WITH CONVECTION TO DEVELOP IN THE WARM
SECTOR AND MOVE ACROSS WESTERN NY AND PA OVER THE NEXT FEW HOURS
WITH RATES OF 1.5"/HR...AND USE UP THE REMAINING AREAL LIMIT OF
INSTABILITY...AS CENTRAL PA ITSELF REMAINED CLOUDED OVER MUCH OF
THE DAY LIMITING THE ABILITY FOR ADDITIONAL AREAL COVERAGE.

AS INSTABILITY WANES...CONVECTION SHOULD EVOLVE INTO SOLID
MODERATE RAINFALL WITH THE STRENGTHENING DEFORMATION ZONE ALONG
THE TROF ALONG THE GREAT LAKES INTO WESTERN QUEBEC INTO THE LARGER
SYNOPTIC CYCLONE.  THIS WILL BE MODERATE BUT WITH LIMITED MOTION
EAST AND INCREASED SPLIT FLOW ALOFT...ADDITIONAL PIVOT POINTS/VORT
CENTER WILL DEVELOP ALONG THIS BOUNDARY BACKING FLOW NORTH OF THE
CIRCULATIONS FOR INCREASED SHARS STYLE MODERATE
RAINS...COMPOUNDING OVER AREAS AFFECTED EARLIER TONIGHT SHIFTING
FROM FLASHY STYLE TO MORE PROLONGED FLOODING ISSUES OVER A BROADER
AREA. THE 18Z NAM-CONEST AND 12Z ARW MAY BE THE MOST REVEALING OF
THIS PATTERN THOUGH EXACT PIVOT LOCATIONS ARE GOING TO BE
DIFFICULT TO DETERMINE...THOUGH LIKELY NEAR AND JUST NORTH OF THE
NY/PA LINE THROUGH THE EARLY OVERNIGHT.  

GALLINA

ATTN...WFO...BGM...BUF...CLE...CTP...PBZ...

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

LAT...LON   43897618 43437577 42287626 41087784 40577914 
            40718025 40938065 41398101 41858106 42237984 
            42797893 43197902 43367893 43407781 43417676 
            43847645