892  
FXUS62 KCHS 181956  
AFDCHS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHARLESTON SC  
356 PM EDT WED SEP 18 2019  
   
SYNOPSIS
 
 
HIGH PRESSURE WILL PROVIDE NOTICEABLY COOLER AND DRIER  
CONDITIONS THROUGH LATE WEEK AND WILL PREVAIL THROUGH EARLY  
NEXT WEEK. A COLD FRONT COULD PUSH INTO THE REGION AROUND THE  
MIDDLE OF NEXT WEEK.  
 

 
   
NEAR TERM /UNTIL 6 AM THURSDAY MORNING/
 
 
THIS EVENING AND TONIGHT: HIGH PRESSURE WILL BUILD ACROSS THE REGION  
IN WAKE OF A COLD FRONT SHIFTING SOUTH OF THE AREA. HOWEVER, FEW TO  
SCATTERED SHOWERS AND PERHAPS AN ISOLATED THUNDERSTORM IS POSSIBLE,  
MAINLY ACROSS PARTS OF SOUTHEAST GEORGIA WHERE MLCAPE AROUND  
1500 J/KG AND PWATS BETWEEN 1.6-1.8 INCHES REMAIN. EXPECT THE  
BULK OF PRECIP ACTIVITY TO WANE THIS EVENING, THEN DISSIPATE  
AROUND SUNSET DUE TO THE LOSS OF DAYTIME HEATING. FEW TO SCATTERED  
CLOUDS SHOULD THEN CLEAR ACROSS THE AREA FROM NORTH TO SOUTH  
DURING THE FIRST HALF OF THE NIGHT. WEAK COLD AIR ADVECTION  
ASSOCIATED WITH DRY HIGH PRESSURE BUILDING ACROSS THE AREA SHOULD  
HELP MAINTAIN A 5-10 MPH NORTHEAST WIND OVERNIGHT. HOWEVER,  
COLD AIR ADVECTION AND DRIER AIR WILL LIKELY SUPPORT COOLER  
TEMPS, WITH LOWS EVENTUALLY DIPPING INTO THE UPPER 50S TO AROUND  
60 WELL INLAND (COOLEST IN SOUTHEAST SOUTH CAROLINA) AND  
MID/UPPER 60S NEAR THE COAST.  
 

 
   
SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/
 
 
COOLER/DRIER HIGH PRESSURE WILL PREVAIL THROUGH THIS PERIOD. THE  
ONLY WRINKLE WILL BE FOR ISOLATED/SCATTERED SHOWERS WHICH WILL CROSS  
COASTAL WATERS AND DEVELOP ONSHORE WITHIN AN E/NE LOW-LEVEL FLOW  
REGIME. SLIGHT CHANCE POPS ARE LIMITED TO FAR SOUTHERN/COASTAL  
COUNTIES THROUGH THURSDAY, THEN COVERAGE OF SLIGHT CHANCE/CHANCE  
POPS EXPANDS SOMEWHAT LATER THURSDAY NIGHT THROUGH FRIDAY AS A  
COASTAL TROUGH BECOMES MORE PRONOUNCED, WITH HIGHEST POPS ACROSS  
SOUTHERN/COASTAL COUNTIES. LIMITED INSTABILITY DOES NOT JUSTIFY ANY  
MENTION OF THUNDERSTORMS THROUGH THIS PERIOD. FRIDAY NIGHT THROUGH  
SATURDAY, GUIDANCE SUGGESTS THAT THE SURFACE HIGH WILL EXPAND AND  
WILL PUSH THE CHANCE FOR SHOWERS SOUTH OF THE REGION.  
 
OTHERWISE, HIGH TEMPERATURES IN THE UPPER 70S NORTH AND LOWER TO MID  
80S SOUTH WILL WARM INTO THE MIDDLE/UPPER 80S SATURDAY AWAY FROM THE  
BEACHES. THURSDAY NIGHT, LOW TEMPERATURES WILL AVERAGE 55-60F AWAY  
FROM T HE COAST AND 65-70F ON THE BEACHES. LATE FRIDAY NIGHT,  
TEMPERATURES WILL FALL INTO THE UPPER 50S TO MIDDLE 60S INLAND AND  
WILL BOTTOM OUT IN THE UPPER 60S TO MIDDLE 70S ON THE COAST. THE  
MOST NOTICEABLE CHANGE WILL BE THE DRIER AIR MASS FEATURING DAYTIME  
DEWPOINTS IN THE 50S/60S THROUGH THIS PERIOD.  
 

 
   
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
 
 
DEEP LAYERED RIDGING WILL PERSIST INTO MONDAY AND THEN TEND TO BREAK  
DOWN THEREAFTER. MODELS HINT AT A WEAK FRONT AND STRONGER NORTHWEST  
FLOW ALOFT BY MID-WEEK, HOWEVER THE DEPTH OF DRY-LAYERED AIR WAS  
STILL ENOUGH TO KEEP MENTIONABLE POPS OUT OF THE FORECAST. TEMPS ARE  
EXPECTED TO RUN ABOVE CLIMO EACH DAY WITH A RETURN TO SOME 90 DEGREE  
HIGH TEMPS EARLY NEXT WEEK INLAND AND SOUTHERN ZONES.  
 

 
   
AVIATION /20Z WEDNESDAY THROUGH MONDAY/
 
 
A FEW SHOWERS COULD POTENTIALLY BRING BRIEF MVFR CONDITIONS AT THE  
SAV TERMINAL LATE THIS AFTERNOON INTO EARLY EVENING. OTHERWISE,  
VFR CONDITIONS ARE EXPECTED AT BOTH CHS AND SAV TERMINALS  
THROUGH 18Z THURSDAY. NORTHEAST WINDS COULD GUST TO 15-20 KT  
NEAR 18Z THURSDAY.  
 
EXTENDED AVIATION OUTLOOK: VFR CONDITIONS WILL PREVAIL.  
 

 
   
MARINE
 
 
THIS EVENING AND TONIGHT: HIGH PRESSURE WILL BUILD ACROSS COASTAL  
WATERS THROUGH TONIGHT BEHIND A DEPARTING COLD FRONT TO THE SOUTH. A  
FAIR AMOUNT OF COLD AIR ADVECTION ASSOCIATED WITH A NORTHEAST WIND  
ALONG WITH LONG PERIOD SWELLS NEAR 11 SECONDS WILL RESULT IN ONGOING  
SMALL CRAFT ADVISORIES FOR ALL WATERS OUTSIDE THE CHARLESTON HARBOR  
THROUGH TONIGHT. SOME GUIDANCE SUGGESTS WINDS COULD INCREASE TOWARD  
DAYBREAK THURSDAY, NECESSITATING A SMALL CRAFT ADVISORY IN THE  
CHARLESTON HARBOR. IN GENERAL, NORTHEAST WINDS WILL GUST TO  
20-25 KTS WHILE SEAS BUILD UP TO 5-7 FT IN NEARSHORE WATERS AND  
7-10 FT IN OFFSHORE GEORGIA WATERS.  
 
A TIGHT NORTHEAST GRADIENT ENHANCED BY HIGH PRESSURE CENTERED NORTH  
OF THE WATERS WILL MAINTAIN HAZARDOUS WINDS/SEAS THROUGH FRIDAY.  
NORTHEAST WINDS AVERAGING 20-25 KNOTS WITH GUSTS TO 30 KNOTS WILL  
CONTRIBUTE TO COMBINED SEAS TOPPING OUT AT 5-8 FEET NEARSHORE WATERS  
AND 8-12 FEET BEYOND 20 NM, WITH WORST CONDITIONS THURSDAY THROUGH  
THURSDAY NIGHT. SMALL CRAFT ADVISORIES ARE IN EFFECT FOR ALL WATERS  
OUTSIDE CHARLESTON HARBOR, AND WIND GUSTS COULD APPROACH SCA LEVELS  
EVEN ON THE HARBOR THURSDAY.  
 
FRIDAY AND ESPECIALLY FRIDAY NIGHT, THE PRESSURE GRADIENT/  
ASSOCIATED WINDS WILL RELAX. WHILE SCA SEAS COULD PERSIST INTO THE  
WEEKEND OVER THE OUTER GA WATERS, OVERALL WE CAN EXPECT A MUCH MORE  
TRANQUIL REGIME THIS WEEKEND INTO EARLY NEXT WEEK. LONG PERIOD SWELL  
CREATED BY OFFSHORE TC JERRY COULD REACH COASTAL WATERS BY EARLY  
NEXT WEEK.  
 
RIP CURRENTS: HIGH RISK OF RIP CURRENTS ON ALL BEACHES THROUGH  
THURSDAY EVENING DUE TO STRONG NORTHEAST WINDS AND AT LEAST A  
2-3 FT/11 SECOND PERIOD SWELL CREATED BY OFFSHORE HURRICANE  
HUMBERTO. AN ELEVATED RISK FOR RIP CURRENTS WILL THEN CONTINUE  
THROUGH AT LEAST THE END OF THIS WEEK.  
 

 
   
TIDES/COASTAL FLOODING
 
 
LOW CHANCES FOR MINOR SALT WATER FLOODING AROUND THE TIMES OF HIGH  
TIDE THROUGH LATE WEEK, ESPECIALLY ALONG THE SOUTH CAROLINA COAST.  
 

 
   
CHS WATCHES/WARNINGS/ADVISORIES
 
 
GA...HIGH RIP CURRENT RISK THROUGH THURSDAY EVENING FOR GAZ117-119-  
139-141.  
SC...HIGH RIP CURRENT RISK THROUGH THURSDAY EVENING FOR SCZ048>051.  
MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT FRIDAY FOR AMZ350-352-354.  
SMALL CRAFT ADVISORY UNTIL 4 AM EDT SUNDAY FOR AMZ374.  
 

 
 

 
NEAR TERM...DPB  
SHORT TERM...SPR  
LONG TERM...  
AVIATION...DPB/SPR  
MARINE...DPB/SPR  
TIDES/COASTAL FLOODING...  
 
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