MESOSCALE PRECIPITATION DISCUSSION 0098
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
144 AM EDT MON JUN 10 2013
 
AREAS AFFECTED...NRN VA...D.C....CENTRAL MD INTO SERN PA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 100543Z - 100943Z
 
SUMMARY...FLASH FLOOD THREAT IS INCREASING AS NOCTURNAL CONVECTION
EXPANDS WITHIN A VERY MOIST ENVIRONMENT OVER THE NEXT SEVERAL
HOURS. 

DISCUSSION...RECENT RADAR TRENDS HAVE SHOWN AN UPTICK IN
CONVECTION WITHIN A VERY MOIST ENVIRONMENT CHARACTERIZED BY
PRECIPITABLE WATER VALUES OF 1.5 TO 1.75 INCHES PER BLENDED TPW
SATELLITE PRODUCT. CELLS ARE GENERALLY MOVING FROM SSW TO NNE
WITHIN THE MEAN FLOW AHEAD OF AN UPPER TROUGH  MOVING INTO THE
OHIO VALLEY THIS MORNING.

LITTLE CHANGE IS EXPECTED TO OCCUR TO THE STEERING FLOW AND RECENT
CONVECTIVE DEVELOPMENT JUST WEST OF THE RICHMOND METRO AREA IS
EXPECTED TO TRACK NNEWD OVER THE WASHINGTON D.C. METRO AREA. FFG
VALUES ARE RELATIVELY LOW DUE TO RECENT RAINS ASSOCIATED WITH
POST-TROPICAL ANDREA...ON THE ORDER OF 1 IN/HR...WHICH ARE LIKELY
TO BE MET WITHIN THE THREAT AREA THROUGH AT LEAST 1000 UTC.

OTTO

ATTN...WFO...PHI...AKQ...CTP...LWX...

ATTN...RFC...MARFC...

LAT...LON   37907822 38467838 39767731 40277626 40467527 39787514
            38507622 37717753 37907822