MESOSCALE PRECIPITATION DISCUSSION 0461
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1151 AM EDT THU AUG 20 2015
 
AREAS AFFECTED...DC, MD, DE, CENTRAL PA, WESTERN NY 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 201550Z - 202150Z
 
SUMMARY...THUNDERSTORMS ARE EXPECTED TO OVERSPREAD THE REGION WITH
INCREASING RAINFALL RATES. FLASH FLOODING IS POSSIBLE.

DISCUSSION...A CONVERGENCE ZONE FROM WESTERN NEW YORK TO THE
EASTERN SHORE WILL BE THE FOCUS FOR INCREASED CONVECTION INTO THE
AFTERNOON. MIXED LAYER CAPE VALUES BETWEEN 500-1000 J/KG ARE
SLOWLY INCREASING ACROSS THE REGION AND PWATS AROUND 2" SHOULD
SUPPORT INCREASING RAINFALL RATES INTO THE AFTERNOON. 

A HIGH CAPE-LOW SHEAR ENVIRONMENT ACROSS THE EASTERN SHORE WILL
ALLOW FOR SLOW MOVING CONVECTION TO PRODUCE LOCALIZED FLASH
FLOODING. STRONGER LOW LEVEL INFLOW ACROSS CENTRAL PA AND WESTERN
NY SHOULD ALLOW FOR BETTER ORGANIZED CONVECTION. CELL TRAINING AND
CELL MERGERS ARE THE MAIN FLASH FLOOD THREAT. MESOSCALE GUIDANCE
SUGGESTS LOCALIZED RAINFALL TOTALS OF 3-4" ARE POSSIBLE.

KREKELER/ROTH

ATTN...WFO...AKQ...BGM...BUF...CTP...LWX...PBZ...PHI...

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

LAT...LON   42737783 42717687 42327633 41627602 40507588 
            39897562 39267536 38587498 37627512 37117564 
            37137600 37387620 37957640 38677688 39197747 
            39877824 40637874 41477875 42207838