MESOSCALE PRECIPITATION DISCUSSION 0375
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1110 PM EDT SAT SEP 13 2014
 
AREAS AFFECTED...SOUTHERN NC/EASTERN SC/SOUTHEASTERN GA... 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 140309Z - 140724Z
 
SUMMARY...SLOW-MOVING CONVECTION HAS BEGUN FOCUSING ALONG A
STALLED FRONTAL ZONE ALONG THE GA/SC COAST. FARTHER INLAND...AN
AREA OF THUNDERSTORMS HAVE BECOME QUASI-STATIONARY AND FOCUSED
ALONG THE COMPLEX TERRAIN. EXPECT FLASH FLOODING TO BE POSSIBLE
GIVEN ABUNDANT MOISTURE AND INSTABILITY WHICH SHOULD BE SLOW TO
ERODE.

DISCUSSION...MID-LEVEL HEIGHT FALLS HAVE CEASED ACROSS THE
SOUTHEASTERN U.S. ALLOWING THE BAROCLINIC ZONE TO STALL FROM
SOUTHERN GA UP ALONG THE SC/NC COASTLINE. ABUNDANT MOISTURE HAS
POOLED ALONG THIS BOUNDARY WITH THE 00Z CHS RAOB INDICATING 2.27"
PWATS IN PLACE. FOR MID-SEPTEMBER...THIS IS CLOSE TO THE 99TH
PERCENTILE BASED ON THE PLOT COURTESY OF WFO RAPID CITY.
ADDITIONALLY...THE PROFILE WAS NEARLY SATURATED TO AROUND 300 MB
INDICATIVE OF HOW MOIST THE TROPOSPHERE IS OVER THE REGION. THERE
IS STILL PLENTY OF INSTABILITY OBSERVED WITH CAPE VALUES
APPROACHING 3000 J/KG. WHILE THE LOSS OF HEATING WILL REDUCE THE
AMOUNT OF INSTABILITY...THE 02Z RAP SHOWS AT LEAST 1000 J/KG OF
MIXED-LAYER CAPE REMAINING ALONG THE SC COAST BY 07Z. THE
LOW-LEVEL INFLOW INTO THE REGION IS WEAK WITH 5 KNOTS OR SO
OBSERVED OUT OF THE SOUTH-SOUTHEAST ON THE VAD WIND PROFILERS.
HOWEVER...THE LAYER EXTENDING FROM 850-MB UP TO THE TROPOPAUSE
CONTAIN WEAK NORTHERLY FLOW WHICH HAS RESULTED IN SMALL CORFIDI
VECTORS. SUCH A REGIME WILL ENHANCE THE THREAT FOR FLASH FLOODING
ALONG THE GA/SC COAST. FARTHER INLAND...EXPECT THE ACTIVITY TO
CONTINUE AS WEAK UPSLOPE FLOW PERSISTS WITHIN THE VERY MOIST
ENVIRONMENT.

AMONG THE AVAILABLE HIGH-RESOLUTION MODELS...THE 00Z HRRR PAINTS
VERY HEAVY RAINFALL ACROSS SOUTHEASTERN GA INTO SOUTHERN SC WITH
AMOUNTS OF 2 TO 4 INCHES THROUGH 09Z. WHILE THERE IS NOT A
CONSISTENT SIGNAL IN THE GUIDANCE...THERE ARE ENOUGH SOLUTIONS
SUGGESTING HEAVY AMOUNTS OVERNIGHT THAT AN MPD IS WARRANTED.


RUBIN-OSTER

ATTN...WFO...CAE...CHS...FFC...GSP...ILM...JAX...RAH...TAE...

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

LAT...LON   35518189 35368060 34917954 33887912 33117946 
            32598023 31888091 30738195 30768280 31388317 
            32378256 33038157 33788117 34398135 34898229