MESOSCALE PRECIPITATION DISCUSSION 0162
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
553 PM EDT SUN MAY 31 2015
 
AREAS AFFECTED...NORTHERN PENNSYLVANIA...SOUTHERN NEW
YORK...NORTHERN NEW JERSEY...CONNECTICUT 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 312152Z - 010352Z
 
SUMMARY...SMALL SCALE POCKETS OF HEAVY RAINFALL WITH SOME ISOLATED
FLOODING CONCERNS IN THE NEAR TERM...WITH INCREASING COVERAGE AND
GENERAL EASTWARD PROGRESSION...REPEAT TRACKS COULD INCREASE AREAL
COVERAGE OF FLASH FLOODING THREATS BY 03Z.  

DISCUSSION...PER 1842Z SPENES AND RECENT ANALYSIS FIELDS...FRONTAL
BOUNDARY DRAPED ACROSS PENNSYLVANIA INTO SOUTHERN NEW ENGLAND HAS
ACTED AS A DIFFERENTIATING BOUNDARY BETWEEN DEEP CONVECTIVE
ELEMENTS WITH TOTAL PWATS IN THE RANGE OF 1.5-1.6" ALLOWING FOR
SOME ISOLATED FLASH FLOODING CONCERNS WITH RATES IN THE 1.5-2"/HR
RANGE...THIS THREAT CONTINUES FURTHER EAST ACROSS LONG ISLAND AND
CONNECTICUT IN THE SHORTER TERM. 
IN FURTHER COORDINATION WITH NESDIS SATELLITE METEOROLOGIST AND
GIVEN INCREASED COVERAGE OF COLD TOPPED CONVECTION ALONG THE
FRONTAL BOUNDARY...AREAL THREAT OF FLASH FLOODING WILL INCREASE
OVER THE NEXT 6 HOURS ACROSS THE DISCUSSION AREA WITH REPEAT
TRACKS OF CONVECTION.

THE MCV ACROSS LAKE ERIE WILL CONTINUE TO ADVANCE ALONG THE
FRONTAL BOUNDARY WHILE STRENGTHENING AND FOCUSING THE LOW LEVEL
FLOW FROM THE SOUTH TO GREATER THAN 35 KTS IN A NARROWLY FOCUSED
JET  PRECEDING THE SURFACE LOW.  THIS SHOULD ACT AS THE CATALYST
TO ADVECT UNTAPPED INSTABILITIES AND MOISTURE ACROSS MID-ATLANTIC
TO ALLOW FOR CONTINUED CONVECTION ALONG THE DRAPING COLD FRONT FOR
CONVECTION WITH AN ADDITIONAL 1-2" TOTALS COMPOUNDING TO THE 1-3"
TOTALS LAID DOWN BY THESE PRIOR BANDS/CLUSTERS...INCREASING THE
COVERAGE FOR POTENTIAL FLASH FLOODING CONDITIONS. 

ADDITIONALLY...STRONG ISENTROPIC LIFT OVER THE BOUNDARY WILL
INCREASE STRATIFORM RAINS WITH SOME EMBEDDED CONVECTIVE ELEMENTS
NORTH OF THE FRONT INTO SOUTHERN NEW YORK. THOUGH NOT LIKELY
LEADING TO FLASH FLOODING...THIS COULD BE MORE PROLONGED IN
DURATION FOR LONGER TERM FLOODING CONCERNS. 

GALLINA

ATTN...WFO...ALY...BGM...BOX...BUF...CLE...CTP...OKX...PBZ...

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

LAT...LON   42687818 42497520 41957398 41727286 41357211 
            40677225 40367511 40337803 40597987 41868011