MESOSCALE PRECIPITATION DISCUSSION 0382
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
155 PM EDT FRI JUN 23 2017

AREAS AFFECTED...FAR EASTERN OH...WESTERN/CENTRAL PA...NORTHERN
WV...FAR WESTERN MD

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

VALID 231755Z - 232200Z

SUMMARY...SHOWERS AND THUNDERSTORMS WITH LOCALLY HEAVY RAIN WILL
BECOME MORE WIDESPREAD THIS AFTERNOON. SOME FLASH FLOODING WILL BE
POSSIBLE.

DISCUSSION...AS PER SPC MCD #1131...A GRADUAL INCREASE IN THE
INTENSITY AND COVERAGE OF CONVECTION HAS BEEN NOTED OVER SOUTHERN
OH...AND IT IS EXPECTED THAT CONVECTION WILL GRADUALLY BECOME A
BIT BETTER ORGANIZED WITH THE AID OF 40 TO 50 KTS OF EFFECTIVE
BULK SHEAR COUPLED WITH UP TO 1500 J/KG OF SBCAPE...AS THE
CONVECTION ADVANCES FARTHER EAST ACROSS PORTIONS OF FAR NORTHERN
WV AND WESTERN PA OVER THE NEXT FEW HOURS. GIVEN THE INCREASE IN
DIURNAL HEATING/SURFACE INSTABILITY AND WITH A STILL MOISTENING
VERTICAL COLUMN ASSOCIATED WITH THE STRONG MOISTURE TRANSPORT UP
ACROSS THE OH VALLEY IN CONNECTION TO T.D. CINDY...THE CONCERN FOR
HEAVY RAINFALL AND POSSIBLE FLASH FLOODING WILL GROW THIS
AFTERNOON AND ESPECIALLY WITH A MORE ORGANIZED CONVECTIVE
EVOLUTION.

PWATS ARE FORECAST TO RISE LOCALLY TO OVER 2 INCHES WHICH WILL
CONTRIBUTE TO A HIGHLY EFFICIENT RAINFALL ENVIRONMENT FOR ENHANCED
RAINFALL RATES...BUT ADDITIONALLY...THE ADDED COMPONENT OF
MODERATE INSTABILITY WILL SUPPORT THE IDEA OF SOME VERY COLD
CONVECTIVE TOPS THAT WILL ENHANCE RATES FURTHER. RAINFALL RATES OF
AS MUCH AS 2.5 INCHES/HR WILL BE POSSIBLE WITHIN THE STRONGER
CONVECTIVE CORES.

THE LATEST HRRR/HRRRX GUIDANCE MAY BE A BIT UNDERDONE WITH THEIR
RAINFALL POTENTIAL GOING THROUGH THE LATE-AFTERNOON GIVEN THE
LATEST SATELLITE/RADAR TRENDS. THE EXPECTATION IS FOR AS MUCH AS 3
TO 4 INCHES OF RAIN BY LATE-AFTERNOON IN SOME AREAS. THIS WILL BE
TENDING TO FALL OVER AREAS OF LOWER FFG...AND LOCALLY OVER SOME
HIGH TERRAIN...ESPECIALLY WITH CONSIDERATION OF THE LAUREL
HIGHLANDS AND ADJACENT ALLEGHENY FRONT. THE POTENTIAL FOR ENHANCED
RUNOFF AND SOME FLASH FLOODING EXISTS AS A RESULT. STAY TUNED...AS
ADDITIONAL MPDS MAY BE REQUIRED LATER AS THIS EVENT EVOLVES.

ORRISON

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

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

LAT...LON   41837820 41437753 40747751 40067793 39627879
            39307992 39208049 39188132 39508089 39938062
            40298076 40528115 40758166 41018111 41268046
            41737948