MESOSCALE PRECIPITATION DISCUSSION 0287
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1012 PM EDT SUN JUN 10 2018

AREAS AFFECTED...ERN WV...FAR SRN PA...WRN MD...NW VA

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

VALID 110211Z - 110615Z

SUMMARY...LOCALIZED FLASH FLOODING WILL BE POSSIBLE AS CLUSTERS OF
THUNDERSTORMS MOVE NEAR A STATIONARY FRONT TONIGHT. THIS WILL BE
MOST LIKELY FROM FAR NE WV AND FAR WRN MD INTO FAR NRN VA. RAIN
RATES OF 1.0 TO 1.5 IN/HR WILL BE POSSIBLE WITH THE STRONGEST
STORMS...WHICH COULD LEAD TO FLOODING.

DISCUSSION...KPBZ RADAR CONTINUES TO SHOW LOOSELY ORGANIZED
CONVECTIVE CLUSTERS GRADUALLY MOVING EAST...AND SLOWLY SINKING
SOUTH...PRODUCING AN ESE OR SE MOTION NEAR THE BORDER OF WEST
VIRGINIA AND PENNSYLVANIA. FROM THE LATE AFTERNOON INTO THE EARLY
EVENING...THESE CONVECTIVE CLUSTERS PRODUCED HEAVY RAINFALL AND
NUMEROUS FLOOD REPORTS FROM SE OHIO INTO SW PENNSYLVANIA. RAIN
RATES HAVE DECREASED SLIGHTLY SINCE...BUT A FEW POCKETS OF 1.0 TO
1.3 IN/HR RAIN RATES WERE STILL BEING ESTIMATED BY KPBZ RADAR AND
MRMS. THE CONVECTIVE CLUSTERS WILL CONTINUE TO ENCOUNTER SLOWLY
DECREASING INSTABILITY AS THEY TRACK NEAR A STATIONARY FROM
STRETCHING FROM THE FAR WRN TIP OF MARYLAND INTO FAR NRN VIRGINIA.
THE RAP 0-3HR FORECASTS INDICATE A RIBBON OF MODERATE 925MB
FRONTOGENESIS NEAR THE STATIONARY FRONT...AND THAT MAY ALSO HELP
SUSTAIN ORGANIZED CONVECTIVE CLUSTERS DESPITE DIMINISHING
INSTABILITY.

HOWEVER...RAIN RATES MAY CONTINUE TO COME DOWN AND AREAL EXTENT OF
THE HEAVIER RAIN MAY SHRINK IN THE PROCESS. NEVERTHELESS... THE
WEST-EAST ORIENTATION OF SOME OF THE CONVECTIVE CLUSTERS MAY
PROMOTE SOME TRAINING... AND THE ENVIRONMENT REMAINS VERY MOIST
WITH 00Z SOUNDINGS FROM KPIT AND KIAD AROUND 1.6 TO 1.7 INCH
PRECIPITABLE WATER. THIS MAY BE SUFFICIENT TO MAINTAIN A THREAT OF
LOCALIZED FLASH FLOODING ACROSS THE NORTHERN HALF OF THE OUTLINED
DISCUSSION AREA... PARTICULARLY GIVEN LOW FFG VALUES.

FURTHER SOUTH... OBJECTIVELY ANALYZED INSTABILITY IS HIGHER AND
THE 00Z RNK SOUNDING SEEMS TO CONFIRM THIS WITH AROUND 1000 J/KG
OF CAPE. KRLX RADAR SHOWS SOME MORE ISOLATED CONVECTION IN CTRL
WEST VIRGINIA. GIVEN A LACK OF STRONGER FORCING IN THIS REGION...
STORMS MAY REMAIN MORE ISOLATED BUT FFG REMAINS LOW IN SOME OF THE
AREAS FURTHER SOUTH ALONG THE WV-VA BORDER AS WELL. SOME OF THOSE
LOCATIONS ARE AROUND 400 PERCENT OF NORMAL RAINFALL IN THE PAST
TWO WEEKS. THEREFORE AT LEAST A SMALL THREAT OF FLASH FLOODING MAY
EXIST FURTHER SOUTH AND THE DISCUSSION AREA WAS EXTENDED SOUTHWARD
TO CAPTURE THAT POSSIBILITY.

LAMERS

ATTN...WFO...CTP...LWX...PBZ...RLX...RNK...

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

LAT...LON   40197979 40177870 39867754 39287708 38897718
            38507769 38307852 38067956 38208060 39178081
            39758045