MESOSCALE PRECIPITATION DISCUSSION 0367
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
246 PM EDT TUE JUN 21 2016
 
AREAS AFFECTED...PORTIONS OF MD & DE 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 211845Z - 212300Z
 
SUMMARY...THUNDERSTORMS WITH HEAVY RAIN ARE BEGINNING TO SHOW
SEGMENTS OF CELL TRAINING.  WITH HOURLY RAIN RATES UP TO 2.5",
FLASH FLOODING IS A CONCERN.

DISCUSSION...A PAIR OF MESOSCALE BOUNDARIES MEETING NEAR
WASHINGTON D.C. ARE ACTING AS THE FOCUS FOR CONVECTION WITH
OVERSHOOTING TOPS, WITH SOME TRAINING SEGMENTS ACROSS NORTHERN AND
CENTRAL MD.  PRECIPITABLE WATER VALUES OF 1.75" LIE ACROSS THE
REGION PER GPS DATA.  INFLOW AT 850 HPA IS CONVERGENT OUT OF THE
WEST AT 30 KTS.  THE LATEST SPC MESOANALYSIS INDICATE BUBBLES OF
3000+ J/KG MLCAPE ACROSS DE AND NORTHERN VA.

CONVECTION SHOULD CONTINUE TO PROPAGATE EAST-SOUTHEAST AT ~40 KTS,
WITH CELL TRAINING MOST EXPECTED NEAR AND DOWNWIND OF THE THERMAL
BOUNDARY MERGER AND DOWNWIND OF THE POCKET OF HIGH INSTABILITY IN
NORTHERN VA.  SOME SETTLING TO THE SOUTH OF THE THUNDERSTORM
ACTIVITY IS EXPECTED AS THE COLD POOL OVER NORTHERN MD CONTINUES
DROPPING SOUTH.  LOCAL AMOUNTS UP TO 2-4" RANGE ARE EXPECTED,
WHICH COULD FALL QUICKLY.  HOURLY RAIN RATES UP TO 2.5" ARE
SUPPORTED BY THIS ENVIRONMENT AND RECENT RADAR ESTIMATES.  FLASH
FLOODING IS POSSIBLE, PARTICULARLY IN URBAN AREAS.

ROTH

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

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

LAT...LON   39517440 38987475 38077517 37917533 37817595 
            38217691 39157743 39377602