MESOSCALE PRECIPITATION DISCUSSION 0518...CORRECTED
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
934 PM EDT SUN JUL 22 2018

CORRECTED FOR TYPO IN SUMMARY

AREAS AFFECTED...EASTERN NC & SOUTHEAST VA

CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY

VALID 230128Z - 230728Z

SUMMARY...A BAND OF THUNDERSTORMS HAS BEGUN TRAINING FROM SOUTH TO
NORTH ACROSS THE AREA.  HOURLY RAIN TOTALS TO 2.5" WITH LOCAL
AMOUNTS TO 5" ARE POSSIBLE THROUGH 07Z.

DISCUSSION...A SECONDARY WARM CONVEYOR HAS SET UP ACROSS THE AREA,
WHICH IS NEAR A SUBTLE SURFACE DEW POINT GRADIENT.  AN UPPER LEVEL
CIRCULATION ACROSS NORTHWEST SC IS LIKELY ENHANCING DIVERGENCE
ALOFT.  PRECIPITABLE WATER VALUES OF ~2" EXIST IN THE AREA PER THE
MOREHEAD CITY NC SOUNDING.  INFLOW AT 850 HPA IS AROUND 25 KTS PER
VAD WIND PROFILES, WITH EFFECTIVE BULK SHEAR OF 30-40 KTS HELPING
TO ORGANIZE THE BAND.  ML CAPES ARE 2500-3000 J/KG.

THE RAP GUIDANCE SUGGESTS THAT THE MOISTURE AXIS IN THE REGION
REMAINS STEADY STATE THROUGH THE PERIOD.  ANY ATTEMPT AT EASTWARD
PROPAGATION SHOULD BE TEMPERED BY LOW-LEVEL WINDS BEING OUT OF THE
SOUTH-SOUTHEAST, WITH BOUNDARY LAYER MOISTURE CONVERGENCE EXPECTED
TO SHARPEN WITH TIME ACROSS SOUTHEAST NC.  THE FORWARD PROPAGATION
VECTORS BACK SOMEWHAT THROUGH THE PERIOD DESPITE SOME EASTWARD
SHIFT IN THE 1000-500 HPA THICKNESS PATTERN IN NC.  HOURLY RAIN
TOTALS TO 2.5" WITH LOCAL AMOUNTS OF 5" ARE POSSIBLE OVER THE NEXT
SEVERAL HOURS, WITH THE HEAVY RAINFALL THREAT POTENTIALLY
CONTINUING THROUGH THE NIGHT.  WITH SO MUCH MOISTURE AND
INSTABILITY IN PLACE, IT WOULD NOT BE A SURPRISE IF ANOTHER MPD
WERE NEEDED FOR THIS AREA IN SIX HOURS.

ROTH

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

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

LAT...LON   37287670 37187623 36677578 34967592 34557708
            35487720 36247713 37047692