MESOSCALE PRECIPITATION DISCUSSION 0248
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
433 PM EDT SUN AUG 03 2014
 
AREAS AFFECTED...SOUTHWEST PA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 032033Z - 040103Z
 
SUMMARY...AN AREA OF THUNDERSTORMS WITH RAINFALL RATES UP TO 1.5"
AN HOUR IS ABOUT TO MOVE OVER A SATURATED REGION.  FLASH FLOODING
IS POSSIBLE.

DISCUSSION...THE LATEST SPC MESOANALYSIS OF SOUTHWEST PA SHOW THAT
CAPE VALUES HAVE REBOUNDED >1000 J/KG, WHICH WERE LOWER EARLIER
DUE TO THUNDERSTORM ACTIVITY EARLIER IN THE DAY.  LOW-LEVEL INFLOW
IS WEAK, INDICATING THAT THE STORMS SHOULD BE OUTFLOW-DOMINANT. 
WITH A DEEP-LAYERED LOW TO ITS NORTHEAST, THE THUNDERSTORMS SHOULD
CONTINUE SWEEPING SLOWLY SOUTHEAST WITH TIME.  

PRECIPITABLE WATER VALUES ARE 1.25-1.5", ON THE THRESHOLD FOR
FLASH FLOODING.  THIS REGION WAS SATURATED FROM RAINFALL
YESTERDAY, WHICH INCREASES THE FLASH FLOOD THREAT FROM WHAT ONE
WOULD NORMALLY EXPECT.  THOUGH THE NEIGHBORHOOD PROBABILITIES FROM
THE 12Z SSEO MEAN SHOW A MINIMAL SIGNAL, RAINFALL RATES FROM THE
CCX RADAR INDICATE LOCAL RAINFALL RATES OF 1.5" AN HOUR ARE
OCCURRING, WHICH WOULD EASILY COMPROMISE THE LOW FFGS. FLASH
FLOODING IS CONSIDERED POSSIBLE HERE UNTIL 01Z.

ROTH

ATTN...WFO...CTP...LWX...PBZ...CLE...

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

LAT...LON   40877738 39917775 39557849 39597916 39827996 40508033
            41248026 41757992 41657961 41087907 41347804 41357758
            40877738