Flash Flood Guidance
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000
AWUS01 KWNH 270214
FFGMPD
VAZ000-NCZ000-270615-

MESOSCALE PRECIPITATION DISCUSSION 0494
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1013 PM EDT TUE JUL 26 2016

AREAS AFFECTED...CENTRAL AND SOUTHERN VA...NORTHERN NC

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

VALID 270210Z - 270615Z

SUMMARY...SLOW-MOVING THUNDERSTORMS WITH INTENSE RAINFALL RATES
MAY CAUSE SOME FLASH FLOODING OVER THE NEXT COUPLE OF HOURS.

DISCUSSION...A SHORTWAVE TROUGH MOVING ACROSS CENTRAL WV AT THIS
TIME IS INTERACTING WITH A VERY MOIST AND UNSTABLE AIRMASS OVER
CENTRAL/SOUTHERN VA AND DOWN INTO NORTHERN NC. THIS IS FOSTERING
CLUSTERS OF SLOW-MOVING THUNDERSTORMS.

THE PWATS ARE RUNNING AS HIGH AS 2 TO 2.2 INCHES BASED ON THE
LATEST RAP ANALYSIS...WITH MLCAPE VALUES OF 1500 TO 2000 J/KG. THE
CONVECTIVE TOPS CONTINUE TO COOL AND THERE HAVE BEEN OCCASIONAL
OVERSHOOTING TOPS NOTED WITH THE GOES-OTD ALGORITHM. GIVEN THE
VERY COLD TOPS/STRONG INSTABILITY-DRIVEN ASCENT AND HIGH PWAT
ENVIRONMENT...RAINFALL RATES OF OVER 2.5 INCHES/HR ARE EXPECTED
WITHIN THE STRONGER CONVECTIVE CLUSTERS.

THE CONVECTION SHOULD GRADUALLY ADVANCE EAST-SOUTHEAST OVER THE
NEXT FEW HOURS TOWARD SOUTHEAST VA...WITH SOME ADDITIONAL CLUSTERS
OF THUNDERSTORMS EXPECTED TO EVOLVE OVER NORTHERN NC. SOME BRIEF
TRAINING OF THE CONVECTIVE CELLS WILL BE POSSIBLE...AND THUS
EXPECT RAINFALL AMOUNTS OF AS MUCH AS 3 TO 4 INCHES THROUGH
06Z...WITH SOME ISOLATED HEAVIER AMOUNTS. THUS...EXPECT SOME FLASH
FLOODING TO BE POSSIBLE AND ESPECIALLY NEAR ANY OF THE URBAN
CENTERS. WILL CONTINUE TO MONITOR.

ORRISON

...PLEASE SEE WWW.WPC.NCEP.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...AKQ...LWX...RAH...RNK...

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

LAT...LON   38007773 37937718 37457669 36907682 36467707
            36037762 35637831 35667911 35857929 36347958
            36548031 36888049 37168014 37497953 37887859



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