Graphic for MPD #0670
MESOSCALE PRECIPITATION DISCUSSION 0670...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1017 PM EDT FRI AUG 11 2017

CORRECTED FOR VALID TIME TO 600Z

AREAS AFFECTED...SE PA...W/SW NJ...DE...CENTRAL AND E MD

CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE

VALID 120205Z - 120600Z

SUMMARY...WARM AIR ADVECTION AND TRAINING CONVECTION MAY CONTINUE
TO POSE FLASH FLOODING CONCERNS IN EARLY OVERNIGHT HOURS.

DISCUSSION...EXPERIMENTAL GOES-16 WV LOOP DENOTES WAVE ACROSS THE
GREAT LAKES CONTINUING TO AMPLIFY UPSTREAM. ADDITIONALLY A
SOUTHERN STREAM SHORTWAVE IN WV AND ITS ASSOCIATED
ANTICYCLONICALLY CURVED OUTFLOW JET COMBINED TO SUPPORT A SOLID
DYNAMICAL ENVIRONMENT FOR WAA ACROSS THE MID-ATLANTIC AND BROAD
SCALE ASCENT.

CURRENT RADAR MOSAIC SHOWS A DECAYING SUPERCELL ACROSS SE MD THAT
HAS BEEN PRODUCING LOCALLY 2-3" (ISOLATED 4") THAT HAS BEEN
ENHANCED BY ADDITIONAL SWLY WAA INDUCED CELLS THAT HAVE THE
POTENTIAL TO CROSS THE TRACK OF THE SUPERCELL MAINTAINING ANY
ONGOING FLOODING CONCERNS THROUGH THE EARLY OVERNIGHT.

FURTHER NORTH AT THE NORTHERN INFLECTION OF THE WAA COINCIDENT
WITH THE BEST LEFT EXIT ASCENT FROM SOUTHERN SHORTWAVE OUTFLOW JET
STREAK...CURRENT IR TREND SUGGEST A CLASSIC HEAVY RAINFALL WEDGE
SIGNATURE IS FORMING ACROSS S CENTRAL PA JUST NORTH OF HARRISBURG
IN THE GREATEST AREA OF DIFFLUENCE ALOFT.  SIMILAR TO FURTHER
SOUTH WAA WILL CONTINUE TO PROVIDE MST FLUX AS WELL AS ISENTROPIC
ASCENT ACROSS LINGERING N-S FRONTAL BOUNDARY. THIS WHILE MEAN FLOW
IS NEARLY ALIGNED TO SUPPORT SOME (THOUGH NOT IDEAL ANGLE) FOR
TRAINING ACROSS S CENTRAL PA INTO SE PA.  LOWER FFG VALUES/URBAN
CENTERS IN THE VICINITY WILL ONLY FURTHER COMPLICATE ANY POSSIBLE
FLASH FLOODING CONCERNS. 

GALLINA

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

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

LAT...LON   41067575 40737451 39667497 38407508 38207605
            38427721 38847759 39277755 40207766 40897633
           


Last Updated: 1017 PM EDT FRI AUG 11 2017