MESOSCALE PRECIPITATION DISCUSSION 0255
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
738 PM EDT FRI JUN 01 2018

AREAS AFFECTED...WESTERN VA INTO NORTHERN MD

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

VALID 012340Z - 020340Z

SUMMARY...CONVECTION TRACKING OVER AREAS WITH WET SOILS COULD POSE
A FLASH FLOOD THREAT INTO THE EVENING HOURS.

DISCUSSION...REGIONAL RADARS SHOWED SCATTERED CONVECTION ACROSS
WESTERN VA THIS EVENING. DESPITE MLCAPE VALUES BETWEEN 1000-1500
J/KG OF MLCAPE...THE CONVECTION HAS REMAINED SCATTERED...AS THE
BEST SYNOPTIC SCALE ASCENT ASSOCIATED REMAINS WEST OF THE REGION.
EVEN THOUGH THE CONVECTION IS SCATTERED...BURSTS OF COLDER CLOUD
TOPS ON THE GOES-16 CLEAN IR LOOP SUGGEST THAT THE CELLS ARE STILL
STRENGTHENING IN THE AXIS OF INSTABILITY IN PLACE.

THE MAIN THREAT WITH THE CELLS IS HEAVY RAINFALL...AS THE
CONVECTION IS CROSSING AN AXIS OF 2.00 INCH PRECIPITABLE WATER
EXTENDING ACROSS WESTERN INTO CENTRAL VA. THE KLWX RADAR INDICATED
HOURLY RAINFALL RATES OF 1.50 INCHES WITH CELLS OVER GREENE
COUNTY, IN AREAS WHERE THE FLASH FLOOD GUIDANCE IS LOW DUE TO
EARLIER HEAVY RAINFALL. THUS FAR...THE CONVECTION HAS REMAINED
PROGRESSIVE IN THE WEST SOUTHWEST MID LEVEL FLOW.

HOWEVER...WEAKENING PROPAGATION VECTORS CENTRAL VIRGINIA INTO
NORTHERN MD COULD ALLOW CELLS TO PRESENT A SHORT TERM TRAINING
THREAT...ESPECIALLY OVER WESTERN INTO NORTHERN VA. THE MOST RECENT
HRRR SHOWED THE POTENTIAL FOR LOCAL 3.00+ INCH RAINFALL AMOUNTS
OVER NORTHERN VA. GIVEN THE WET SOILS IN PLACE, LOCALLY HEAVY
RAINFALL...ESPECIALLY WHERE CONVECTION TRAINS...POSES A FLASH
FLOOD THREAT. HOWEVER...GIVEN THE SCATTERED NATURE TO THE
CONVECTION THUS FAR....FLASH FLOODING IS ONLY CONSIDERED POSSIBLE
THAT THIS JUNCTURE.

HAYES

ATTN...WFO...CTP...LWX...

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

LAT...LON   39737705 39437671 38687721 38647763 38597785
            38207844 38227864 38357879 38767884 39327854
            39697797