521  
FXUS62 KCHS 271956  
AFDCHS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHARLESTON SC  
356 PM EDT MON MAR 27 2017  
 
...HIGH RISK FOR RIP CURRENTS ALONG THE LOWER SOUTH CAROLINA  
COAST TUESDAY...  
   
SYNOPSIS
 
 
ATLANTIC HIGH PRESSURE WILL WEAKEN THROUGH TUESDAY. A WEAK COLD  
FRONT WILL STALL OVER OR NEAR THE AREA ON WEDNESDAY. ANOTHER  
COLD FRONT WILL MOVE THROUGH FRIDAY NIGHT INTO SATURDAY FOLLOWED  
BY DRIER HIGH PRESSURE SUNDAY.  
 

 
   
NEAR TERM /THROUGH TONIGHT/
 
 
THROUGH SUNSET: ISOLATED SHOWERS/TSTMS WILL REMAIN POSSIBLE  
THROUGH SUNSET ALONG/WEST OF THE INLAND MOVING SEA BREEZE.  
POPS AROUND 20% WILL BE MAINTAINED.  
 
TONIGHT: PERSISTENT ATLANTIC HIGH PRESSURE WILL FINALLY BEGIN  
TO RELENT OVERNIGHT AS A COLD FRONT APPROACHES FROM THE WEST.  
AFTERNOON CONVECTION WILL QUICKLY END WITH THE LOSS OF  
INSOLATION AND EXPECT MOSTLY DRY CONDITIONS TO PREVAIL THROUGH  
THE EVENING HOURS. THE RISK FOR PRECIPITATION WILL INCREASE  
EARLY TUESDAY MORNING AS A POTENT SOUTHERN STREAM SHORTWAVE AND  
THE ATTENDANT COLD FRONT DRAW CLOSER. THE BULK OF THE STRONG  
DPVA/FORCING LOOKS TO PASS WELL TO THE NORTH WITH ONLY THE TAIL  
END BRUSHING AREAS ADJACENT TO THE CSRA AND SOUTHERN MIDLANDS.  
THIS SHOULD BE ENOUGH FOR AN AREA OF ISOLATED SHOWERS/TSTMS TO  
MOVE ACROSS THE NORTHERN PORTIONS OF THE FORECAST AREA; ROUGHLY  
ALONG/NORTH OF A MILLEN-WALTERBORO-DOWNTOWN CHARLESTON LINE.  
WILL CARRY 20% POPS IN THESE AREAS WITH NON-MENTIONABLE POPS  
ELSEWHERE. ALTHOUGH SURFACE BASED INSTABILITY WILL BE AT A  
MINIMUM, MODELS SHOW FAIRLY DECENT MID-LEVEL LAPSE RATES WITH  
CORRESPONDING SHOWALTER VALUES DROPPING TO -1 TO -2C. THIS COULD  
BE JUST ENOUGH TO SUPPORT A FEW RUMBLES OF THUNDER. LOWS WILL  
RANGE FROM WITHIN A DEGREE OR TWO OF 60 INLAND WITH LOWER 60S AT  
THE COAST.  
 

 
   
SHORT TERM /TUESDAY THROUGH THURSDAY/
 
 
THE UPPER SHORTWAVE WILL BE MOVING OFF THE SC COAST BY EARLY  
TUESDAY AFTERNOON, TAKING WITH IT THE BEST CHANCE FOR SHOWERS  
AND TSTMS. WE MAINTAINED A SLIGHT CHANCE FOR PRECIP ACROSS FAR  
NORTHERN AREAS WHERE THE BETTER FORCING WILL EXIST.  
 
THE UPPER RIDGE WILL EXPAND TO THE EAST ON WEDNESDAY WHILE A  
WEAK BACK DOOR COLD FRONT DROPS IN FROM THE NORTH. DESPITE A  
WEAK NORTHERLY SURFACE FLOW DEVELOPING, DOWNSLOPE COMPONENT  
ALOFT AND LARGE-SCALE WARM AIR ADVECTION SHOULD RESULT IN WARM  
TEMPERATURES IN THE MID/UPPER 80S.  
 
THE UPPER RIDGE WILL HANG ON INTO THURSDAY THOUGH SOME SHORTWAVE  
ENERGY LIFTING OUT OF THE CENTRAL GULF WILL YIELD INCREASING  
ISENTROPIC ASCENT ACROSS THE STALLED FRONT. SCATTERED SHOWERS  
WILL BE POSSIBLE OVER THE CENTRAL AND SOUTHERN AREAS, WITH  
THUNDERSTORMS POSSIBLE FARTHER TO THE SOUTH WHERE A BIT MORE  
SURFACE-BASED INSTABILITY DEVELOPS.  
 

 
   
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/
 
 
THE STALLED FRONT ACROSS GA IS EXPECTED TO SHIFT NORTH AS A WARM  
FRONT THURSDAY NIGHT INTO FRIDAY FOLLOWED BY A COLD FRONTAL PASSAGE  
SATURDAY. DRIER HIGH PRESSURE LOOKS TO THEN RETURN LATER IN THE  
WEEKEND BEFORE MORE UNSETTLED WEATHER POSSIBLY MOVES BACK INTO THE  
AREA FOR NEXT MONDAY. SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE  
THROUGH FRIDAY NIGHT, ALTHOUGH THE BEST CHANCES AND HEAVIEST AMOUNTS  
ARE LIKELY THROUGH FRIDAY MORNING. TEMPERATURES SHOULD REMAIN ABOVE  
NORMAL THROUGH THE PERIOD.  
 

 
   
AVIATION /18Z MONDAY THROUGH SATURDAY/
 
 
VFR. ISOLATED TSTMS ARE EXPECTED TO DEVELOP WEST AND NORTH OF  
THE TERMINALS THIS AFTERNOON AND WILL BE MONITORED. NO DIRECT  
IMPACTS ARE EXPECTED.  
 
EXTENDED AVIATION OUTLOOK: LOW CEILINGS POSSIBLE WED NIGHT  
THROUGH THU NIGHT AS A FRONT STALLS OVER THE AREA. BRIEF FLIGHT  
RESTRICTIONS POSSIBLE IN SHOWERS AND TSTMS THU NIGHT THROUGH FRI  
NIGHT.  
 

 
   
MARINE
 
 
TONIGHT: SOUTHERLY FLOW REGIME WILL PERSIST OVERNIGHT THE AREA  
WILL REMAIN SITUATED BETWEEN HIGH PRESSURE WELL OFFSHORE AND A  
COLD FRONT TO THE WEST. SPEEDS WILL REMAIN 10 KT OR LESS WITH  
SEAS 2-4 FT NEARSHORE WATERS AND 4-5 FT GEORGIA OFFSHORE WATERS.  
 
TUESDAY THROUGH SATURDAY: STRENGTHENING EAST TO SOUTHEAST FLOW  
THURSDAY INTO FRIDAY WILL RESULT IN INCREASING SEAS, WITH 6  
FOOTERS REACHING THE GULF STREAM BY THURSDAY NIGHT. AT LEAST 6  
FT SEAS EXPECTED OVER ALL COASTAL MARINE ZONES ON FRIDAY,  
GRADUALLY SUBSIDING FRIDAY NIGHT INTO SATURDAY AS THE SURFACE  
HIGH SHIFTS EAST. SMALL CRAFT ADVISORIES APPEAR LIKELY FOR MUCH  
OF THE AREA DURING THIS TIME.  
 
RIP CURRENTS: 3 FT 10 SEC SWELL, INCREASING ONSHORE WINDS AND  
ASTRONOMICAL INFLUENCES WILL YIELD A HIGH RISK FOR RIP CURRENTS  
ALONG THE SC COAST AND MODERATE FOR GA ON TUESDAY. THE SWELL  
WILL BE DECREASING ON WEDNESDAY THOUGH THE RISK WILL LIKELY  
REMAIN ELEVATED AT LEAST UNTIL THEN.  
 

 
   
TIDES/COASTAL FLOODING
 
 
HIGH TIDES COULD REACH ADVISORY LEVELS, MAINLY LATE  
WEDNESDAY/THURSDAY, DUE TO STRENGTHENING ONSHORE WINDS AND  
SWELLS IMPACTING THE COAST. THIS COULD CAUSE SHALLOW SALTWATER  
INUNDATION IN TYPICALLY VULNERABLE COASTAL AREAS, ESPECIALLY IN  
SC.  
 

 
   
CHS WATCHES/WARNINGS/ADVISORIES
 
 
GA...NONE.  
SC...NONE.  
MARINE...NONE.  
 

 
 

 
 
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