MESOSCALE PRECIPITATION DISCUSSION 0143
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
151 AM EDT MON JUL 01 2013
 
AREAS AFFECTED...EXTREME NERN MD...ERN PA...SERN NY AND NWRN NJ 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 010550Z - 011100Z
 
SUMMARY...CLUSTERS OF HEAVY SHOWERS AND THUNDERSTORMS ARE EXPECTED
TO INCREASE IN COVERAGE THE NEXT FEW HOURS. WET ANTECEDENT
CONDITIONS SHOULD FOSTER INCREASING SHORT-TERM FLASH FLOOD
CONCERNS.

DISCUSSION...A WEAK SHORTWAVE IMPULSE EMBEDDED WITHIN DEEP S/SWLY
FLOW ALONG THE EAST COAST IS SEEN LIFTING NNEWD OUT OF NC AND INTO
CNTRL/SRN VA ATTM. THIS ENERGY SHOULD LIFT STEADILY NNEWD
OVERNIGHT INTO THE CHEASAPEAKE BAY REGION WHILE TENDING TO HELP
CONCENTRATE AND ENHANCE THE BKN CLUSTERS OF CONVECTION SEEN
CURRENTLY OVER FAR NERN MD AND INTO SERN PA. THE LATEST RAP
ANALYSIS SHOWS A NOSE OF SBCAPE VALUES OVER 1000 J/KG OVER THE
CHESAPEAKE BAY AREA AND UP ACROSS NERN MD AND INTO FAR SERN PA.
THIS INSTABILITY AXIS COUPLED WITH LOCALIZED UPSLOPE
FLOW/OROGRAPHIC FORCING AND MODEST DEEP LYR ASCENT ASSOCD WITH THE
AFOREMENTIONED SHORTWAVE SHOULD SUPPORT THE ACTIVITY. POTENTIAL
EXISTS FOR THE BKN CLUSTERS TO ATTAIN SOME BETTER ORGANIZATION
FARTHER NORTH ACROSS ERN AND NERN PA OVER THE NEXT FEW HOURS WITH
THE AID OF EVEN STRONGER OROGRAPHICS AND PRESENCE OF A WEAK
FRONTAL ZONE.

VERY WET ANTECEDENT CONDITIONS OVER MUCH OF ERN PA...SERN NY AND
EXTREME NWRN NJ...COUPLED WITH RAINFALL RATES OF 1 TO 2 INCH/HR
WITH THE DEVELOPING ACTIVITY WILL FOSTER AT LEAST SOME SHORT-TERM
FLASH FLOOD CONCERNS...ESPECIALLY OVER AREAS OF HIGHER TERRAIN.

ORRISON

ATTN...WFO...OKX...ALY...PHI...BGM...CTP...LWX...

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

LAT...LON   42207558 41497654 40827718 40237730 39767703 39537668
            39477616 39767562 40297503 40827455 41207435 41807428
            42267470 42207558