MESOSCALE PRECIPITATION DISCUSSION 0460
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
505 PM EDT SUN JUL 15 2018

AREAS AFFECTED...SOUTHWEST PA...CENTRAL/EASTERN WV...WESTERN VA

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

VALID 152105Z - 160100Z

SUMMARY...SLOW-MOVING AND LOCALLY BACKBUILDING THUNDERSTORMS WILL
PROMOTE LOCALIZED FLASH FLOODING CONCERNS INTO THE EARLY EVENING
HOURS.

DISCUSSION...THE LATEST RADAR IMAGERY SHOWS NUMEROUS SHOWERS AND
THUNDERSTORMS IMPACTING THE CENTRAL APPALACHIANS WITH A FOCUS FROM
THE LAUREL HIGHLANDS OF SOUTHWEST PA AND SOUTH DOWN THE SPINE OF
ALLEGHENIES ACROSS WESTERN MD AND THROUGH CENTRAL WV. POCKETS OF
STRONG CONVECTION ARE ALSO NOTED EAST OF THE APPALACHIAN CREST AND
GENERALLY WEST OF THE BLUE RIDGE INVOLVING THE WV/MD PANHANDLES
AND ALSO ADJACENT AREAS OF FAR WESTERN VA.

THE CONVECTION IS FOCUSING NEAR A WEAK MID LEVEL SHEAR AXIS AND IS
BEING FURTHER AIDED BY OROGRAPHIC FORCING/TERRAIN CIRCULATIONS AND
MODERATE BUOYANCY COURTESY OF STRONG DIURNAL HEATING.
ADDITIONALLY...THE COLUMN IS QUITE MOIST WITH PWATS GENERALLY
AROUND 1.75 INCHES.

HEAVY RAINFALL RATES OF UP TO 2 INCHES/HR WILL BE EXPECTED THROUGH
THE AFTERNOON AND EARLY EVENING HOURS WHICH WILL LIKELY CAUSE SOME
AREAS OF FLASH FLOODING...AND ESPECIALLY WITH RATHER SLOW CELL
MOTIONS. STORM TOTALS OF AS MUCH AS 3 TO 4+ INCHES WILL BE
POSSIBLE THROUGH 00Z. EXPECT THE ACTIVITY TO BEGIN WEAKENING
THOUGH EARLY THIS EVENING AS INSTABILITY BECOMES INCREASINGLY
EXHAUSTED.

ORRISON

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

ATTN...RFC...LMRFC...MARFC...OHRFC...SERFC...

LAT...LON   40587969 40427904 40077829 39397781 38917779
            38367809 37747871 37407959 36738043 36538090
            36618133 36878140 37578134 38358109 38848095
            39478094 40008098 40458038