MESOSCALE PRECIPITATION DISCUSSION 0270...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
806 PM EDT THU JUN 25 2015

CORRECTED FOR RAINFALL RATE MENTION IN SUMMARY
 
AREAS AFFECTED...CNTRL/ERN VIRGINIA INTO NERN NORTH CAROLINA 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 252322Z - 260522Z
 
SUMMARY...A FEW LOCATIONS ACROSS CNTRL AND ERN VIRGINIA INTO NERN
NORTH CAROLINA COULD SEE FLASH FLOODING WITH 3 HOUR RAINFALL RATES
OF 3 INCHES POSSIBLY DEVELOPING EARLY TONIGHT.  

DISCUSSION...23Z SURFACE ANALYSIS SHOWED A DEVELOPING AREA OF LOW
PRESSURE NEAR CHO WITH A SLOWLY LIFTING WARM FRONT EXTENDING SEWD
TO THE ERN VIRGINIA/NORTH CAROLINA BORDER. CLOUD COVER ACROSS NRN
VIRGINIA DURING THE AFTERNOON HAS LIMITED THE DEGREE OF
INSTABILITY BUT LATEST SPC MESOANALYSIS INDICATES ANYWHERE BETWEEN
1000 AND 2500 J/KG MLCAPE IS IN PLACE TO THE SOUTH...FROM THE
PIEDMONT OF CNTRL VIRGINIA AND WRN PORTIONS OF THE COASTAL PLAIN
TO THE CNTRL VIRGINIA/NORTH CAROLINA BORDER. 

THE LATEST PRECIPITABLE WATER VALUES PER AREA GPS SITE SENSORS
SHOW 1.7 TO 2.0 INCHES PRESENT ALONG THE VIRGINIA/NORTH CAROLINA
BORDER...NEAR THE 95TH PERCENTILE. CONVECTIVE COVERAGE IS EXPECTED
TO INCREASE ALONG THE SERN FLANK OF AN APPROACHING SHORTWAVE
CURRENTLY OBSERVED ON WATER VAPOR IMAGERY OVER NRN WEST VIRGINIA
INTO S-CNTRL PENNSYLVANIA. WHILE CONVECTIVE ALLOWING MODELS AGREE
ON THIS IDEA AND SHOW CONVECTION TO BE PROGRESSIVE OFF TO THE
SOUTHEAST...IN AGREEMENT WITH UPWIND PROPAGATION CORFIDI
VECTORS...INCREASING LOW LEVEL FLOW OVERNIGHT MAY ALLOW FOR SOME
TRAINING TO TAKE PLACE ACROSS SERN VIRGINIA INTO NRN NORTH
CAROLINA GIVEN LOW LEVEL WINDS APPROACHING FORECAST MEAN STORM
CELL MOTIONS. THIS WOULD BE OF SPECIAL CONCERN FOR LOCATIONS
SOUTHWEST OF NORFOLK WHERE AN ESTIMATED 1-2 INCHES OF RAIN HAS
FALLEN FROM EARLIER CONVECTION THIS EVENING.

THIS IDEA IS SUPPORTED BY A SOUTHWARD ADJUSTMENT TO 12Z
NMM/ARW/NSSL WRF...18Z NAM CONEST AND BY RECENT HRRR AND
EXPERIMENTAL HRRR RUNS...MAINLY AFTER 03Z.

OTTO

ATTN...WFO...AKQ...LWX...MHX...PHI...RAH...RNK...

ATTN...RFC...MARFC...SERFC...

LAT...LON   38797632 38317532 37257535 36177564 35867671 
            35757882 36377967 37247893 37937827 38367755