Graphic for MPD #0619

MESOSCALE PRECIPITATION DISCUSSION 0619
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
304 AM EDT THU AUG 03 2017

AREAS AFFECTED...COASTAL SC

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

VALID 030703Z - 031303Z

SUMMARY...THUNDERSTORMS ARE INCREASING ACROSS THE COASTAL PLAIN OF
SOUTHERN SC.  HOURLY RAIN RATES UP TO 2.5" WITH LOCAL AMOUNTS TO
4" ARE POSSIBLE.

DISCUSSION....A LOW-LEVEL CYCLONIC CIRCULATION LIES ACROSS THE
SOUTHEAST GA COASTAL PLAIN NEAR SAVANNAH.  THIS IS OCCURRING SOUTH
OF A SHORTWAVE MOVING THROUGH WESTERN NC, NOTED ON RECENT WATER
VAPOR IMAGERY.  A THERMAL BOUNDARY TO ITS EAST-NORTHEAST IS ACTING
AS A FOCUS FOR SHOWERS AND THUNDERSTORMS WITH COOLING CLOUD TOPS
PER EXPERIMENTAL GOES-16 10.7 MICRON CLEAR CHANNEL IR IMAGERY. 
PRECIPITABLE WATER VALUES ARE ESTIMATED NEAR 2" IN THIS REGION,
MAINLY BASED ON RAP ANALYSES.  INFLOW AT 850 HPA IS CYCLONIC AND
AROUND 30 KTS PER THE JACKSONVILLE FL VAD WIND PROFILE AND RECENT
RAP ANALYSES.  EFFECTIVE BULK SHEAR OF 25 KTS IS ADVERTISED IN
RECENT SPC MESOANALYSES, WHICH SHOULD LEAD TO SOME LEVEL OF
ORGANIZATION.  RECENT RADAR REFLECTIVITY APPEARED TO SHOW A VAGUE
ROTATION IN SOUTHERN SC.  MU CAPE VALUES ARE 1000-2000 J/KG.

THE EXPECTATION IS FOR THUNDERSTORMS TO TRY TO SPREAD UP THE COAST
OF SC WITH TIME.  CONVECTION SHOULD KEEP THE LOW-LEVEL BOUNDARY
FROM MOVING TOO MUCH FARTHER NORTHWARD, BUT SOME AREAS OF THE
COAST HAVE CIN WHICH COULD LEAD TO ELEVATED CONVECTION CLOSER TO
THE 850 HPA SLICE OF THE BOUNDARY.  FORWARD PROPAGATION PARALLEL
TO THE COAST COULD OCCUR FOR A SHORT SPELL, BUT IN AREAS WHERE CIN
DOES NOT EXIST, THE BOUNDARY COULD SHIFT SLIGHTLY SOUTHEAST,
LEADING TO UNCERTAINTY REGARDING LOCAL MAXIMA ANTICIPATED AND HOW
FAR INLAND HEAVY RAINFALL MIGHT PROGRESS.  THE AVAILABLE MOISTURE,
INSTABILITY, AND LIFT SHOULD LEAD TO HOURLY RAIN RATES UP TO 2.5".
 PER COORDINATION WITH THE CHS/CHARLESTON SC OFFICE, LOCAL MAXIMA
AROUND 4" ARE POSSIBLE THROUGH 13Z.

ROTH

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

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

LAT...LON   33647927 33617899 32927928 32308047 32268115
            32438195 32898126 33538001


Last Updated: 304 AM EDT THU AUG 03 2017