MESOSCALE PRECIPITATION DISCUSSION 0668
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
525 PM EDT FRI AUG 11 2017

AREAS AFFECTED...CENT PA...N VA...E WV PANHANDLE...W CENT MD...S
NY

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

VALID 112125Z - 120200Z

SUMMARY...CONVECTION WITH ORIENTATION PARALLEL TO THE FLOW ALONG
WITH UPSTREAM REDEVELOPMENT SUPPORT SOME TRAINING AND POSE
LOCALIZED FLASH FLOOD RISK

DISCUSSION...EXPERIMENTAL GOES-16 WV LOOP DEPICTS BROAD CYCLONE
OVER THE GREAT LAKES CURRENTLY WITH A SUBTLE TWIST NEAR LAKE ERIE.
 ADDITIONALLY...ANTICYCLONICALLY CURVED 80KT JET STREAK IS
CROSSING S OHIO/N KY.  THIS PLACES CENTRAL PA WITHIN DIFFLUENT
LEFT EXIT REGION WITH FAIRLY STRONG DPVA UPSTREAM ALLOWING FOR
FAIRLY STRONG SYNOPTIC ASCENT WITH GOOD POTENTIAL FOR
BACKBUILDING.  ADDITIONALLY THIS ALLOWS FOR SOLID MOISTURE
TRANSPORT FROM THE SOUTH THROUGH THE N-S OROGRAPHY OFF THE
ATLANTIC (PER CIRA LAYERED PW ANALYSIS) TO INCREASE ABOVE BOUNDARY
LAYER MOISTURE PROFILES TO REACH TPW AROUND 1.75" TO MATCH
BOUNDARY LAYER CONDITIONS WITH UPPER 60S TO 70F TDS.

CURRENT RADAR MOSAIC SUGGESTS SEVERAL CONVECTIVE LINES THAT HAVE
DEVELOPED ALONG THE MAIN RIDGE BETWEEN CBE TO AOO TO W OF IPT AND
HAS SHOWN SOME UPSTREAM REDEVELOPMENT.  THIS DEVELOPMENT IS
ORIENTED FAVORABLY WITH THE 8-4H MEAN WIND TO SUPPORT REPEATING
OVER THE NEXT FEW HOURS. GIVEN AVAILABLE MOISTURE...RAIN RATES OF
1.5-2"/HR ARE POSSIBLE AND GIVEN DURATION OF THE REPEATING THERE
IS A POTENTIAL FOR SOME LOCALS FOR 3-4" POSSIBLY HIGHER (THOUGH
19Z HRRR APPEARS OVERDONE WITH 6"+ IN SULLIVAN/LUZERNE COUNTY).  
HI-RES CAMS ALSO SUGGEST THE THREAT WILL CONTINUE TO TRACK NE WITH
TIME PLACING SIMILAR RAINFALL RATES/TOTALS IN THE VICINITY OF
LOWER FFG VALUES OF THE CATSKILLS AND E POCONOS.  AS SUCH FLASH
FLOODING IS CONSIDERED POSSIBLE PARTICULARLY THROUGH ROUGHED
MOUNTAIN TERRAIN.  

GALLINA

ATTN...WFO...ALY...BGM...CTP...LWX...OKX...PHI...

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

LAT...LON   42527500 42347411 41617435 40237600 39377660
            38667738 38817862 39717849 41087838 42467579