MESOSCALE PRECIPITATION DISCUSSION 0234
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
502 PM EDT WED MAY 30 2018

AREAS AFFECTED......WESTERN SC AND NORTH CAROLINA TO THE TN
BORDER...

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

VALID 302100Z - 310300Z

SUMMARY...SHOWERS ARE DEVELOPING THIS AFTERNOON AND EVENING IN
AREAS WHERE RAINFALL AND FLOODING OCCURRED LAST NIGHT...WITH
LOCALLY HEAVY DOWNPOURS LIKELY AND FLOODING PROBLEMS POSSIBLE

DISCUSSION...RADAR AND SATELLITE TRENDS SHOW AN UPTICK IN SHOWERS
ACROSS GA AND THE CAROLINAS.  CLUSTERS OF SHOWERS ARE DEVELOPING
DOWNSTREAM FROM THE 850-700 MB TROUGH IN GA.  THESE SHOWERS SHOULD
MOVE NORTHEAST ACROSS FAR EASTERN TN AND WESTERN SC AND NC OVER
THE NEXT SEVERAL HOURS.

RADAR SHOWS A BAND OF SHOWERS FROM AN OLD OUTFLOW BOUNDARY
CROSSING GA TO COMBINE WITH RAP MODEL FORECAST 700 MB ASCENT/300
MB DIVERGENCE MAXIMA TO AID IN DEVELOPING SHOWERS THAT WILL MOVE
INTO WESTERN SOUTH CAROLINA THIS EVENING. SATELLITE WATER VAPOR
IMAGERY SHOWS A SURGE IN MID-HIGH LEVEL MOISTURE CROSSING FROM GA
INTO THE CAROLINAS. FORECAST SOUNDING SHOW AREAS OF LAYER 90
PERCENT RELATIVE HUMIDITY...LEADING TO EFFICIENT RAINFALL
PROCESSES.

AREAS OF 1-2 INCHES OF RAIN ARE LIKELY WHERE HEAVIER DOWNPOURS
PERSIST.
GIVEN THE HEAVIER PATCHES OF RAIN AND FLOODING LAST NIGHT...FLASH
FLOOD GUIDANCE HAS LOWERED TO 1.5 INCHES IN 6 HOURS AND THIS COULD
BE MET WHERE CELL MERGERS OCCUR IN WESTERN NC AND SC.

SEVERAL RUNS OF THE HIGH RES RAPID REFRESH (HRRR) AND THE WRF
ARW/ARW 2 SHOW LOCAL BANDS AND CLUSTERS OF 1-2 INCHES.  THE 18Z
NAM CONUS NEST SHOWS 1-3 INCHES OF RAIN IN NORTHWEST SC TO
SOUTHWEST NC THROUGH THIS EVENING WITH LOCALLY HIGHER AMOUNTS IN
THE 12Z NAM AND 19Z HRRR. 

PETERSEN

ATTN...WFO...FFC...GSP...MRX...RNK...

ATTN...RFC...LMRFC...OHRFC...SERFC...

LAT...LON   36558108 36488078 36188072 35808107 35368148
            35008215 34578270 34528306 34788344 35228403
            35788307 36418199