Flash Flood Guidance
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000
AWUS01 KWNH 140733
FFGMPD
NCZ000-SCZ000-GAZ000-141132-

MESOSCALE PRECIPITATION DISCUSSION 0376
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
332 AM EDT SUN SEP 14 2014

AREAS AFFECTED...FAR SOUTHEASTERN GA/SOUTHERN SC/SOUTHEASTERN
NC...

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

VALID 140732Z - 141132Z

SUMMARY...THE MORE ORGANIZED THREAT FOR FLASH FLOODING HAS SHIFTED
INTO MUCH OF THE SOUTHERN HALF OF SC. THE STRONGER ECHOES HAVE
FOCUSED SOUTHEAST OF THE KCAE RADAR WHERE 2 TO 3 INCH HOURLY RATES
HAVE BEEN NOTED VIA DUAL-POL ALGORITHMS. EXPECT THE THREAT FOR
FLASH FLOODING TO CONTINUE THROUGH THE EARLY MORNING HOURS.

DISCUSSION...THE 07Z SURFACE ANALYSIS INDICATED A WAVY FRONTAL
BOUNDARY STRETCHED FROM CENTRAL GA UP THROUGH COASTAL SC AND ALONG
THE GULF STREAM. STRONG LOW-LEVEL CONVERGENCE WAS NOTED IN THE
OBSERVATIONS WITH THE 06Z RAP CONFIRMING THIS WITH A LOCAL MAXIMA
IN THE 1000-925 MB MASS FLUX CONVERGENCE OVER SOUTHERN SC. THIS
WAS WHERE SOME OF THE DEEPER CONVECTION WAS OCCURRING JUST SOUTH
OF COLUMBIA SC WITH DOPPLER ESTIMATES OF 2 TO 3 INCHES OF RAINFALL
PER HOUR. WHILE THE BETTER INSTABILITY WILL CONTINUE TO DECREASE
IN TIME...THERE SHOULD BE ENOUGH MID-LEVEL FORCING FROM AN
UPSTREAM IMPULSE TRACKING THROUGH SOUTHWESTERN NC TO KEEP AN
ORGANIZED THREAT OF HEAVY RAINFALL. MOISTURE REMAINS LOCKED IN
PLACE WITH 2 TO 2.25 INCH PWATS LINGERING ALONG THE STALLED
FRONTAL ZONE. THE CURRENT GPS DERIVED PWATS SUGGESTS A SIMILAR
TROPOSPHERIC MOISTURE PROFILE TO THE 00Z RAOBS OVER THE REGION.
EXPECT SLOW CELL MOTIONS TO PRODUCE AREAS OF FLASH
FLOODING...PARTICULARLY IN REGIONS CURRENTLY PRECIPITATING WHERE
SOILS ARE BECOMING SATURATED.

THE 00Z HRW-ARW...HRW-NMMB ARE FAIRLY CONSISTENT WITH WHAT THE 00Z
NAM CONTEST/NSSL WRF/SPC WRF ARE SHOWING PAINTING AN AXIS OF HEAVY
PRECIPITATION OVER THE MPD AREA THROUGH 12Z. THIS RAISED
CONFIDENCE IN ISSUING A DISCUSSION FOR THESE AREAS. THE PRIMARY
THREAT WILL BE EARLY IN THE PERIOD WHERE THE INSTABILITY WILL BE
MAXIMIZED.


RUBIN-OSTER

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

ATTN...WFO...CAE...CHS...ILM...

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

LAT...LON   34547795 34267707 33727684 33267720 33127816
            32957921 32158069 32438158 33148203 34028194
            34438132 34348000



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