MESOSCALE PRECIPITATION DISCUSSION 0096
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
646 PM EDT FRI JUN 07 2013
 
AREAS AFFECTED...SOUTHEAST VA...EASTERN MD...DE...NJ...LONG ISLAND
NY...CT...RI...SOUTHEAST MA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 072245Z - 080305Z
 
SUMMARY...VERY HEAVY RAINFALL CONTINUES TO STREAM NORTHEAST OF THE
CENTER OF ANDREA -- NOW A POST- TROPICAL CYCLONE -- AND A SECOND
LOW PRESSURE AREA MOVING INTO NJ ALONG A STATIONARY FRONT.  THE
SYSTEM HAS A HISTORY OF FLASH FLOODING FROM NC INTO THE EASTERN
MID-ATLANTIC STATES.

DISCUSSION...A VERY MOIST AIR MASS IS PRESENT NEAR AND WELL
NORTHEAST OF THE CENTER OF WHAT WAS ONCE TROPICAL CYCLONE ANDREA
WHICH HAS NOW COMPLETED EXTRATROPICAL TRANSITION AND BECOME A
COASTAL LOW.  A SECOND LOW PRESSURE AREA TO ITS NORTHEAST IS
MOVING INTO SOUTHWEST NJ.  THE SYSTEMS ARE LINKED BY A FRONTAL
ZONE WHICH IS EDGING EASTWARD TOWARDS THE WESTERN ATLANTIC. 
PRECIPITABLE WATER VALUES -- PW -- LIE BETWEEN 2-2.5 INCHES WHICH
IS NEAR THE 99TH PERCENTILE FOR THE REGION DURING THE MONTH OF
JUNE.  A BAND OF CONVECTION EXTENDS ALONG THE FRONT FROM SOUTHEAST
VA NORTHEAST ACROSS THE EASTERN SHORE OF THE CHESAPEAKE, NJ, AND
LONG ISLAND TOWARDS SOUTHERN NEW ENGLAND ALONG A STATIONARY FRONT
WHERE LOW- TO MID-LEVEL FRONTOGENESIS IS PRESENT AND IS EXPECTED
TO INTENSIFY INTO TONIGHT WHICH COULD INCREASE PRECIPITATION
EFFICIENCY ACROSS THE REGION, PARTICULARLY SOUTHERN NEW ENGLAND. 
BROAD DIVERGENCE EXISTS OVER THE REGION EAST OF AN UPPER LEVEL
TROUGH.  LOCAL RAINFALL AMOUNTS OF 2-4 INCHES WITHIN A FEW HOURS
WILL LEAD TO FLASH FLOODING WITHIN THIS REGION, PARTICULARLY URBAN
AREAS OF SOUTHEAST VA, DE, NJ, LONG ISLAND NY, AND SOUTHERN NEW
ENGLAND, SO HAVE INDICATED THE LIKELY CATEGORY FOR THIS AREA.

ROTH

ATTN...WFO...BOX...OKX...ALY...PHI...AKQ...LWX...

ATTN...RFC...MARFC...NERFC...SERFC...

LAT...LON   37857482 36757620 36967733 38927645 41457434 42277180
            41626993 37857482