MESOSCALE PRECIPITATION DISCUSSION 0729
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
830 AM EDT SAT OCT 08 2016
 
AREAS AFFECTED...CENTRAL AND EASTERN SC AND NC 
 
CONCERNING...HEAVY RAINFALL...FLASH FLOODING LIKELY 
 
VALID 081229Z - 081900Z
 
SUMMARY...HURRICANE MATTHEW IS EXPECTED TO PRODUCE AN ADDITIONAL
4-8 INCHES OF RAINFALL...WITH LOCALLY HIGHER AMOUNTS...THROUGH 3
PM EDT ACROSS CENTRAL AND EASTERN PORTIONS OF SOUTH CAROLINA AND
NORTH CAROLINA

DISCUSSION...AT 12Z...NHC PLACED THE CENTER OF HURRICANE MATTHEW
ABOUT 20 MILES SSE OF CHARLESTON, SC. ADDITIONALLY, A
QUASI-STATIONARY COASTAL FRONT WAS ANALYZED GENERALLY ALONG THE
COAST OF THE CAROLINAS. INFRARED SATELLITE IMAGERY SHOW THAT
MATTHEW CONTINUES TO MAINTAIN A CORE OF DEEP CONVECTION NEAR THE
CENTER, WITH CLOUD TOP TEMPERATURES AROUND -76 DEG C. THESE CLOUD
TOPS HAVE WARMED ONLY VERY SLIGHTLY OVER THE PAST FEW HOURS.
RECENT RADAR ESTIMATED AND GAUGE VERIFIED RAINFALL RATES OF 1-2
IN/HR HAVE BEEN OCCURRING IN THE NORTHERN SIDE OF THE EYEWALL
WHICH HAS BEEN MOVING ALONG THE COASTLINE NEAR CHARLESTON, SC.
FARTHER NORTH, AN ADDITIONAL BAND OF HEAVY RAINFALL IS OCCURRING
NORTH OF THE STATIONARY FRONT IN A BAND OF LOW/MID-LEVEL
FRONTOGENETIC FORCING. RAINFALL RATES IN THIS AREA, CURRENTLY
OBSERVED FROM NEAR COLUMBIA, SC EAST TO THE NC BORDER, ARE IN THE
1-1.5 IN/HR RANGE. 

INSTABILITY IS MARGINAL PER LATEST SPC MESOANALYSIS, WITH MOST
UNSTABLE CAPES IN THE 500-1000 J/KG RANGE SOUTH/EAST OF THE
STATIONARY FRONT AND IN THE 100-500 J/KG RANGE JUST NORTH/WEST OF
THE FRONT. GIVEN THE STRONG AND BROAD 50-60 KT LOW-LEVEL
CROSS-FRONTAL FLOW, THIS INSTABILITY IS SUFFICIENT TO SUPPORT
THESE HEAVY RAINFALL RATES.

THE CENTER OF MATTHEW IS FORECAST BY THE NHC TO MOVE GENERALLY
NORTHEASTWARD OVER THE NEXT SEVERAL HOURS ALONG THE SOUTH CAROLINA
COAST. THE LATEST RUNS OF THE RAP SHOW FRONTOGENETIC FORCING
NORTH/WEST OF THE FRONT INCREASING FROM LATE MORNING INTO EARLY
AFTERNOON AS LOW-LEVEL WINDS ON THE COLD SIDE OF THE FRONT BEGIN
TO BACK IN RESPONSE TO THE CENTER OF MATTHEW MOVING NORTHEASTWARD.
AS A RESULT, WOULD EXPECT THE POTENTIAL FOR RAINFALL RATES INLAND
OVER SC AND NC TO INCREASE AS THIS OCCURS, WITH RATES OVER 2 IN/HR
POSSIBLE. NUMEROUS HI-RES MODELS INCLUDING THE
HRRR/HRRR-EXPERIMENTAL, WRF-ARW/NMM, AND NSSL-WRF INDICATE THE
POTENTIAL FOR A BAND OF 4-8 INCH RAINFALL AMOUNTS INLAND FROM THE
FRONT OVER THE NEXT SEVERAL HOURS, WITH LOCALLY HIGHER AMOUNTS.
GIVEN THE ONGOING FLASH FLOODING IN SOME AREAS, AND THE POTENTIAL
FOR THESE ADDITIONAL EXCESSIVE RAINFALL AMOUNTS, FLASH FLOODING IS
LIKELY.

RYAN

ATTN...WFO...AKQ...CAE...CHS...GSP...ILM...MHX...RAH...

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

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            34777643 34577661 34467700 34227732 33977766 
            33697799 33617855 33437878 33157905 32787954 
            32707970 32558013 32638056 32878101 33008135 
            33238167 33798189 34288163 34848101 35218040 
            35767952 36157872