MESOSCALE PRECIPITATION DISCUSSION 0343
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
243 PM EDT MON JUN 19 2017

AREAS AFFECTED...SERN PA...SWRN NJ...DE...MD...VA...NRN NC

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

VALID 191841Z - 200000Z

SUMMARY...POTENTIAL FOR HIGH RAINFALL RATES AS WELL AS LOCALIZED
CELL TRAINING COULD RESULT IN 2-3" RAINFALL AMOUNTS IN 1-2 HOURS,
WITH LOCALLY HIGHER AMOUNTS. FLASH FLOODING IS POSSIBLE.

DISCUSSION...A HIGHLY MOIST AND MODERATELY UNSTABLE AIR MASS IS IN
PLACE ACROSS THE MID-ATLANTIC THIS AFTERNOON AHEAD OF AN INCOMING
COLD FRONT CROSSING THE APPALACHIANS. MLCAPE VALUES RANGING FROM
1500-2500 J/KG WERE INDICATED ON THE LATEST RAP MESOANALYSIS, WITH
PWATS NEAR 2 INCHES. SURFACE DEW POINTS IN THE 68-73 DEG F RANGE
ARE SUPPORTING LOW LCLS (BELOW 1000 M) AND A DEEP WARM CLOUD LAYER
DEPTH EXCEEDING 4.5 KM. LATEST 250 HPA ANALYSIS SHOWS ADDITIONAL
UPPER LEVEL SUPPORT ACROSS THE OUTLINED AREA PROVIDED BY HEALTHY
UPPER DIFFLUENT FLOW. THE RESULT IS THE POTENTIAL FOR VERY HIGH
PRECIPITATION EFFICIENCY AND HEAVY RAINFALL RATES IN ANY ROBUST
CONVECTION THAT OCCURS. LATEST RADAR ESTIMATES INDICATE 2-3 IN/HR
RATES IN THE HEAVIEST CONVECTION ACROSS CNTRL VA.

THE LATEST HRRR RUN SEEMS TO HAVE A DECENT HANDLE ON THE ONGOING
CONVECTION, PARTICULARLY THE MORE ORGANIZED LINE EXTENDING FROM
FROM NORTHERN VA TO SERN PA. HRRR REPRESENTATION OF THE MULTICELL
CLUSTERS FARTHER SOUTH ACROSS VA APPEARS A BIT UNDERDONE. GIVEN A
UNIDIRECTIONAL SHEAR PROFILE AND GREATER AVAILABLE DCAPE, A
STRONGER COLD POOL IS EXPECTED TO DEVELOP IN THE MORE ORGANIZED
CONVECTION ACROSS NRN VA, MD, AND SERN PA, RESULTING IN LESS
POTENTIAL FOR TRAINING. HOWEVER, GIVEN THAT THIS AREA WILL AFFECT
THE I-95 CORRIDOR, THERE IS LESS TOLERANCE FOR HIGH RAINFALL
RATES. LOCALIZED TRAINING IS POSSIBLE FARTHER SOUTH ACROSS CNTRL
AND SRN VA AND NRN NC. INSTANTANEOUS RATES OF 2-3 IN/HR ARE
POSSIBLE IN THE HEAVIEST CONVECTION, WHICH COULD RESULT IN
LOCALIZED AMOUNTS OF 2-4 INCHES IN AREAS OF SIGNIFICANT LOCALIZED
TRAINING. FLASH FLOODING IS POSSIBLE THROUGH 00Z.

RYAN

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

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

LAT...LON   40717615 40327519 38937552 37147705 36357827
            36137900 36127993 36248044 36448100 37098122
            37428044 37638005 38027957 38597858 40057706