MESOSCALE PRECIPITATION DISCUSSION 0669
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
1017 AM EDT WED SEP 14 2016
 
AREAS AFFECTED...COASTAL SC 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING POSSIBLE 
 
VALID 141430Z - 142030Z
 
SUMMARY...BANDING ASSOCIATED WITH JULIA IS EXPECTED TO MOVE ASHORE
ACROSS PORTIONS OF COASTAL SC LATE THIS MORNING INTO THIS
AFTERNOON. THE BANDED CONVECTION COULD RESULT IN A FLASH FLOOD
THREAT.

DISCUSSION...REGIONAL RADARS ACROSS NORTH FL INTO SC SHOWED THAT
BANDED CONVECTION WAS STARTING TO ROTATE BACK TOWARD SOUTHERNMOST
SC THIS MORNING. THE KCHS RADAR INDICATED THAT CONVECTION WITH 
HOURLY RAINFALL RATES GREATER THAN AN INCH ASSOCIATED WITH THE
BANDING WAS ABOUT TO COME ASHORE OVER BEAUFORT COUNTY. 

THE IR LOOP SHOWED COOLING TOPS OFF THE SC COAST...AS CONVECTIVE
BURSTS HAVE ATTAINED CLOUD TOPS TEMPERATURES NEAR -70 CELSIUS WELL
OFFSHORE. THE MOVEMENT OF THE OFFSHORE BANDS WOULD BRING
CONVECTION WITH THE HIGHEST RAINFALL RATES CLOSE TO THE SC COAST
EARLY THIS AFTERNOON. HOWEVER...TO THIS POINT...THE BEST
CONVECTION AND HIGHEST RAINFALL RATES HAVE REMAINED OFFSHORE. 

THERE IS A MULTI MODEL SIGNAL FOR CONVECTIVE BANDS TO BEGIN
AFFECTING MAINLY SOUTH COASTAL SECTIONS OF SC AFTER 15Z...WITH THE
HIGHEST RAINFALL RATES (APPROACHING 2.00 INCHES) BETWEEN 17Z AND
20Z. THE LATEST HRRR/EXPERIMENTAL HRRR SHOWED LOCAL RAINFALL
AMOUNTS OF 4-6 INCHES...CENTERED FROM KNBC TO SOUTH OF KMYR. GIVEN
THE HIGH MOISTURE CONTENT AIR IN PLACE (THE 12Z JAX SOUNDING
SHOWED A  2.30 PRECIPITABLE WATER VALUE)...THESE AMOUNTS SEEMS
PLAUSIBLE. 

THREE HOUR FLASH FLOOD GUIDANCE VALUES ALONG COASTAL SC GENERALLY
REMAIN GREATER THAN 2.50 INCHES...AND THE THREAT FOR FLASH
FLOODING WOULD BE PREDICATED ON MULTIPLE BANDS AFFECTING THE AREA.
GIVEN SOME UNCERTAINTY AS TO THE PLACEMENT OF THE CONVECTIVE BANDS
THROUGH THIS AFTERNOON...FLASH FLOODING IS CONSIDERED POSSIBLE. 

HAYES

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

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

LAT...LON   33837906 33757868 33187884 33147893 31938051 
            31908055 31968089 32478119 32938082 33417987