MESOSCALE PRECIPITATION DISCUSSION 0315
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
122 PM EDT SUN JUN 05 2016
 
AREAS AFFECTED...SOUTH-CENTRAL PA...PANHANDLES OF MD/WV...WESTERN
VA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 051715Z - 052200Z
 
SUMMARY...A BAND OF HEAVY SHOWERS AND THUNDERSTORMS WILL CROSS THE
APPALACHIANS AND MOVE EAST TOWARD THE BLUE RIDGE. HEAVY RAINFALL
RATES UP TO 2 INCHES/HR MAY CAUSE SOME FLASH FLOODING/RUNOFF
PROBLEMS.

DISCUSSION...A PRE-FRONTAL BAND OF SHOWERS AND THUNDERSTORMS IS
MOVING TOWARD CENTRAL PA AND EXTENDS WELL TO THE SOUTHWEST DOWN
ACROSS CENTRAL WV. OVER THE NEXT SEVERAL HOURS THIS ACTIVITY WILL
BE MOVING EAST INTO AN AXIS OF GREATER INSTABILITY AND HIGHER
PWATS. THE LATEST RAP ANALYSIS SHOWS A RIBBON OF 500 TO 1000 J/KG
OF MLCAPE NOSING UP ACROSS THE SHENANDOAH VALLEY AND INTO THE
MD/WV PANHANDLES WEST OF THE BLUE RIDGE. WHILE THIS IS CURRENTLY
VERY MODEST...AN INCREASE IN DIABATIC HEATING WILL FURTHER
DESTABILIZE THE BOUNDARY LAYER AND WILL FOSTER AN ENVIRONMENT FOR
THE UPSTREAM CONVECTIVE ACTIVITY TO FURTHER INTENSIFY.

OBSERVED RAINFALL RATES OVER SOUTHWEST PA HAVE ALREADY BEEN ON THE
ORDER OF 1 TO 1.25 INCHES/HR...AND THE DOWNSTREAM PWAT ENVIRONMENT
EAST OF THE APPALACHIAN CREST AND WEST OF THE BLUE RIDGE IS QUITE
MOIST...WITH PWATS OF 1.6 TO 1.8 INCHES. EVEN HIGHER PWATS ARE
NOTED EAST OF THE BLUE RIDGE. THIS WILL FAVOR INCREASING RAINFALL
RATES WITHIN THE CONVECTIVE BAND AS IT ADVANCES EAST THIS
AFTERNOON...AND IT EXPECTED THAT THESE RATES MAY REACH AS HIGH AS
2 INCHES/HR.

THE CONVECTION WILL BE RATHER PROGRESSIVE IN NATURE THIS
AFTERNOON...BUT RECENT RAINFALL OVER THIS REGION OVER THE LAST
COUPLE OF DAYS HAS LED TO A NOTABLE LOWERING OF FFG VALUES...AND
SO THE INTENSE AFOREMENTIONED RAINFALL RATES OVER JUST A 1 TO 2
HOUR PERIOD MAY BE JUST ENOUGH TO CAUSE SOME FLASH FLOODING AND/OR
RUNOFF PROBLEMS FOR THESE AREAS.

ORRISON

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

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

LAT...LON   40477812 40417755 39877755 39237784 38737830 
            38347837 37947844 37687864 37567909 37348010 
            37028111 37278175 37628180 37948135 38398087 
            38928006 39237954 39477926 40317855