MESOSCALE PRECIPITATION DISCUSSION 0591
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
421 PM EDT SUN AUG 21 2016
 
AREAS AFFECTED...EASTERN MD...DE...CENTRAL/SOUTHERN NJ 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 212015Z - 212315Z
 
SUMMARY...TRAINING THUNDERSTORMS BECOMING MORE OF A CONCERN OVER
THE NEXT COUPLE OF HOURS. FLASH FLOODING WILL BE POSSIBLE.

DISCUSSION...CONVECTIVE CLOUD TOPS HAVE COOLED SIGNIFICANTLY OVER
THE LAST HOUR WITH A SUBSTANTIAL INCREASE IN LIGHTNING ACTIVITY
AND DEVELOPMENT OF A COUPLE OF OVERSHOOTING TOPS WITH THE
CONVECTIVE BAND EXTENDING FROM CENTRAL/SOUTHERN MD NORTHEAST INTO
PARTS OF EASTERN MD/NORTHERN DE AND INTO FAR SOUTHWEST NJ.

PWATS ACROSS THE REGION ARE ALREADY QUITE HIGH UP NEAR 2.25
INCHES...WHICH WILL BE CONDUCIVE TO VERY HEAVY RAINFALL RATES.
HOWEVER...GIVEN THE INCREASED CONVECTIVE ORGANIZATION AND COOLING
CLOUD TOPS...THESE RATES WILL BE ENHANCED FURTHER. THERE HAS BEEN
SOME CELL-TRAINING NOTED NEAR THE NORTHERN CHESAPEAKE BAY AND MOVE
ACROSS PORTIONS OF NORTHEAST MD AND NORTHERN DE OVER THE LAST 30
TO 45 MINUTES.

THE CONVECTION IS FOCUSING OUT AHEAD OF AN APPROACHING COLD
FRONT...AND IS BECOMING A BIT BETTER ORGANIZED AS A RESULT OF
SOMEWHAT STRONGER LOW LEVEL CONVERGENCE/FORCING NEAR THE BAY...AND
ALSO WITH A BIT GREATER INSTABILITY. EXPECT THE POTENTIAL FOR
RAINFALL AMOUNTS OF AS MUCH AS 2 TO 4 INCHES AS THIS BAND OF
CONVECTION MOVES THROUGH OVER THE NEXT 2 TO 3 HOURS.
CONSEQUENTLY...SOME FLASH FLOODING WILL BE POSSIBLE. CONDITIONS
WILL IMPROVE TOWARD EVENING THOUGH AS THE AFOREMENTIONED COLD
FRONT BEGINS TO CROSS THE REGION.

ORRISON

ATTN...WFO...AKQ...PHI...

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

LAT...LON   40037485 40007426 39727424 39287459 38707512 
            38437575 38657630 38967641 39377596 39737536