MESOSCALE PRECIPITATION DISCUSSION 0589
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
713 PM EDT FRI JUL 28 2017

AREAS AFFECTED...SOUTHEAST VA...NORTHEAST NC

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 282315Z - 290415Z

SUMMARY...WARM SECTOR CONVECTION DEVELOPING LIKELY TO TRAVERSE
AREAS AFFECTED BY ONGOING FLOODING CONCERNS. 

DISCUSSION...WITHIN THE LARGER SYNOPTIC SCALE DEVELOPING WAVE IS A
SMALLER SCALE SHORTWAVE EXITING THE CENTRAL APPALACHIANS ATTM IN
NW NC.  RADAR/SATELLITE MOSAICS DENOTE THIS WARM SECTOR WAVE
SHOWING ADDITIONAL FRONTAL STRUCTURE WITH VERY POTENT NORTH-SOUTH
ARC OF CONVECTION WITH SEVERE WINDS CROSSING CENTRAL NC/SC ACTING
AS THE SUB-SCALE COLD FRONT WHILE AN E-W DEFORMATION ZONE
EFFECTIVELY ACTS AS THE WARM FRONT SUPPORTING STRONG CONVECTION
ACROSS THE NORTHERN NECK (SEE MPD 586 FOR MORE DETAILS).

IT IS WITHIN THIS WAVE'S WARM SECTOR... ACROSS THE E
PIEDMONT/COASTAL PLAIN OF SE VA/NE NC THAT NEW CONVECTION AS
RAPIDLY DEVELOPED IN A VERY MOIST/UNSTABLE ENVIRONMENT REPRESENTED
BY MID 80S TS AND LOW TO MID 70S TDS SUPPORTING SBCAPES TO 3000
J/KG.  GIVEN THE OVERALL LARGE SCALE ASCENT IN THE VICINITY FROM
THE DPVA...A FEW CLUSTERS OVER EXPANSIVE AREA (NE OF RAH, W OF
AKQ) HAVE DEVELOPED WITH RATES AOA 2"/HR WHICH HAS THE POTENTIAL
FOR 1-2 HOURS OF DURATION GIVEN ITS AREAL EXPANSE AND POSES A
FLASH FLOODING RISK.  THIS MAY EVEN BE FURTHER EXACERBATED AS THE
PIVOT TO THE WAVE MAY TRACK THROUGH SIMILAR AREAS NEAR/NORTH OF
THE VA/NC LINE.

OF GRAVE CONCERN IS THE SOUTHERN CLUSTER GIVEN ITS TRAJECTORY WILL
BE THROUGH AN AREA ALREADY AFFECTED BY FLASH FLOODING IN NE NC. 
WITH AN ADDITIONAL 2-3" OF RAIN HERE...FLASH FLOODING IS LIKELY TO
CONTINUE.

GALLINA

ATTN...WFO...AKQ...MHX...RAH...

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

LAT...LON   37577632 37527560 36807585 36467575 36037575
            35897669 35727768 35727787 36167847 37147820
            37457744