Flash Flood Guidance
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AWUS01 KWNH 241508
FFGMPD
NCZ000-242000-

MESOSCALE PRECIPITATION DISCUSSION 0114
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1105 AM EDT TUE APR 24 2018

AREAS AFFECTED...EASTERN NC

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

VALID 241500Z - 242000Z

SUMMARY...VERY HEAVY RAINFALL WILL BE IMPACTING EASTERN NC THROUGH
THE LATE-MORNING AND EARLY AFTERNOON HOURS. THE INTENSE RAINFALL
RATES TO OVER 2 INCHES/HR MAY RESULT IN SOME RUNOFF PROBLEMS AND
POSSIBLE FLASH FLOODING.

DISCUSSION...STRONG CONVECTION WITH VERY HRAVY RAINFALL IS
OCCURRING OVER SOUTHEAST NC AROUND THE EASTERN FLANK OF AN UPPER
TROUGH MOVING ACROSS THE CENTRAL APPALACHIANS THIS MORNING. THIS
ENERGY IS INTERACTING WITH A WELL-DEFINED LOW TO MID LEVEL FETCH
OF ATLANTIC MOISTURE THAT HAS BECOME ESPECIALLY FOCUSED ALONG AND
A WARM FRONT THAT IS GRADUALLY LIFTING NORTH UP TOWARD THE
SOUTHEAST NC COASTAL PLAIN AND ALSO UP ALONG AN INVERTED COASTAL
TROUGH THAT IS INLAND OVER FAR EASTERN NC. THE AREA VAD WIND
PROFILER DATA IS INDICATING A 40 TO 50 KT SOUTHEAST LOW LEVEL JET
THAT IS SUPPORTING NOT ONLY ENHANCED MOISTURE CONVERGENCE/FORCING
IN VICINITY OF THE FRONT BUT IS ALSO POOLING A NOSE OF STRONGER
INSTABILITY FROM JUST OFFSHORE AND NEAR THE GULF STREAM WATERS.

THE LATEST GOES-16 SATELLITE IMAGERY INCLUDING 10.3 MICRON/IR AND
DAY CONVECTION RGB DATA SUGGESTS SOME INCREASE IN CONVECTIVE
ORGANIZATION OVER THE LAST 1 TO 2 HOURS AND OBSERVED RAINFALL
RATES ARE REACHING UP BETWEEN 1.5 AND 2 INCHES/HR. THESE RAINFALL
RATES WILL BE AIDED BY THE STRONG FORCING OVER THE NEXT SEVERAL
HOURS SEEN IN THE LOW LEVELS WITH THE ROBUST WARM ADVECTION
PATTERN BUT ALSO WITH DIFFLUENT FLOW ALOFT AND A RELATIVELY DEEP
POOL OF MOISTURE THAT WILL CONTRIBUTE TO GREATER RAINFALL
EFFICIENCY. THUS SOME RAINFALL RATES MAY REACH UP OVER 2 INCHES/HR
GOING INTO THE EARLY AFTERNOON HOURS AS GREATER MOISTURE AND
INSTABILITY CONCENTRATION FOCUSES OVER EASTERN NC IN TIME.

A CONSENSUS OF THE LATEST HIRES CAM GUIDANCE LED BY HRRR...ARW AND
NMMB SUPPORTS ADDITIONAL RAINFALL AMOUNTS OF AS MUCH AS 2 TO 4
INCHES WITH SOME ISOLATED HEAVIER AMOUNTS NOT OUT OF THE QUESTION
UP ALONG THE INVERTED SURFACE TROUGH. SOME RUNOFF PROBLEMS WILL BE
POSSIBLE AND AREAS CLOSER TO THE TROUGH AXIS MAY SEE SUFFICIENT
FOCUSING OF CONVECTION FOR SOME ISOLATED FLASH FLOODING. WILL
CONTINUE TO MONITOR.

ORRISON

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

ATTN...WFO...AKQ...MHX...

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

LAT...LON   36257606 36127554 35607543 35187555 34627635
            34537668 34537721 34847754 35257741 35637714
            35957678



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