649  
FXUS62 KCHS 172038  
AFDCHS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHARLESTON SC  
338 PM EST WED JAN 17 2018  
   
SYNOPSIS
 
 
COLD, DRY HIGH PRESSURE WILL BUILD INTO THE REGION AND PREVAIL  
INTO FRIDAY BEFORE MODERATING TEMPERATURES OCCUR THIS WEEKEND  
INTO EARLY NEXT WEEK. A COLD FRONT WILL PUSH THROUGH THE AREA  
MONDAY, FOLLOWED BY DRY HIGH PRESSURE INTO THE MIDDLE OF NEXT  
WEEK.  
 

 
   
NEAR TERM /UNTIL 6 PM THIS EVENING/
 
 
A CUT-OFF UPPER LOW OVER THE WESTERN CAROLINAS WILL SWING EAST  
TONIGHT AND WILL BE OFF THE COAST BY THURSDAY MORNING.  
MEANWHILE AT THE SURFACE, HIGH PRESSURE WILL BUILD IN FROM THE  
WEST AS LOW PRESSURE LIFTS TO THE NORTHEAST. STRONG FORCING AND  
SOME LINGERING MOISTURE MAY BE ENOUGH TO SUPPORT VERY LIGHT RAIN  
AND MAYBE EVEN A FEW FLURRIES ACROSS THE NORTHERN ZONES EARLY  
BEFORE THE ATMOSPHERE REALLY DRIES OUT. CLOUDS WILL CONTINUE TO  
CLEAR FROM THE SOUTHWEST THROUGH THE EVENING WITH CLEAR SKIES  
EXPECTED BY MIDNIGHT.  
 
STRONG COLD ADVECTION WILL TAKE HOLD TONIGHT WITH TEMPERATURES  
DROPPING TO THE LOW-MID 20S. THESE TEMPERATURES WILL COMBINE  
WITH ELEVATED WINDS TO PRODUCE WIND CHILLS IN THE MID TEENS.  
GIVEN THE COASTAL COUNTY WIND CHILL ADVISORY CRITERIA IS 15  
DEGREES, HAVE RAISED AN ADVISORY FOR 4 AM TO 8 AM. CONDITIONS  
ELSEWHERE (INLAND) ARE NOT EXPECTED TO MEET THEIR RESPECTIVE  
CRITERIA OF 10 DEGREES.  
 

 
   
SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/
 
 
COLD, DRY HIGH PRESSURE WILL CONTINUE TO BUILD IN BEHIND A  
SHARP UPPER SHORTWAVE TROUGH THURSDAY, THEN PREVAIL INTO FRIDAY  
BEFORE TEMPERATURES MODERATE TO ABOVE NORMAL LEVELS SATURDAY.  
MANY AREAS WILL START THURSDAY MORNING IN THE LOWER TO MID 20S  
AND THIS WILL CAUSE WIND CHILLS NEAR 15 DEGREES. MOST AREAS WILL  
BE BACK INTO THE 20S FRIDAY MORNING, EVEN CLOSE TO FREEZING AT  
THE COAST.  
 

 
   
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
 
 
HIGH PRESSURE WILL PREVAIL OVER THE SOUTHEAST UNITED STATES LATE  
WEEKEND INTO EARLY NEXT WEEK BEFORE A COLD FRONT ARRIVES MONDAY. THE  
PATTERN WILL FAVOR WARMING CONDITIONS UNDER RIDGING ALOFT. IN  
GENERAL, AFTERNOON HIGHS WILL PEAK IN THE MID/UPPER 60S ON SUNDAY.  
BY MONDAY, SOUTHERLY WINDS WILL HELP ADVECT DEEP MOISTURE OVER THE  
SOUTHEAST AND PRODUCE SOME CLOUD COVER AHEAD OF THE APPROACHING  
FRONT. THIS COULD LIMIT OVERALL HEATING POTENTIAL, BUT A PREVAILING  
SOUTHERLY FLOW SHOULD STILL SUPPORT TEMPS IN THE UPPER 60S FOR MOST  
LOCATIONS IN SOUTHEAST SOUTH CAROLINA TO AROUND 70 DEGREES IN  
SOUTHEAST GEORGIA AHEAD OF COLD FRONT. CHANCES OF SHOWERS SHOULD  
ARRIVE TO MOST AREAS MONDAY AFTERNOON AS THE FRONT BEGINS TO SHIFT  
OVER THE REGION. DRY HIGH PRESSURE WILL THEN RETURN ON TUESDAY AND  
PERSIST INTO THE MIDDLE OF NEXT WEEK. TEMPS WILL BE SLIGHTLY COOLER  
BEHIND THE FRONT, BUT SHOULD REMAIN A FEW DEGREES ABOVE NORMAL. IN  
GENERAL, TUESDAY AND WEDNESDAY AFTERNOON TEMPS SHOULD PEAK IN THE  
LOWER 60S. OVERNIGHT LOWS SHOULD RANGE IN THE LOW/MID 40S.  
 

 
   
AVIATION /21Z WEDNESDAY THROUGH MONDAY/
 
 
SOME LOW CLOUDS ARE LINGERING BEHIND A COLD FRONT THAT PUSHED  
OFFSHORE THIS MORNING. THERE COULD BE A BRIEF PERIOD OF SUB-VFR  
CIGS THIS AFTERNOON AND HAVE INCLUDED BEST TIMING IN THE TAF.  
ALSO COULDN'T RULE OUT LIGHT PRECIP AT KCHS THIS AFTERNOON/EARLY  
EVENING. CONDITIONS WILL IMPROVE TONIGHT AND VFR IS EXPECTED BY  
EARLY THURSDAY MORNING.  
 
EXTENDED AVIATION OUTLOOK: NO SIGNIFICANT CONCERNS.  
 

 
   
MARINE
 
 
STRONG PRESSURE RISES AND ONGOING COLD ADVECTION WILL RESULT IN  
SMALL CRAFT ADVISORIES FOR ALL WATERS OUTSIDE OF THE CHARLESTON  
HARBOR TONIGHT. NORTHWEST WINDS WILL PEAK IN THE 15-25 KNOT  
RANGE WITH GUSTS OF 25-30 KT. SEAS ON AVERAGE WILL BE 3 TO 5  
FEET NEARSHORE, 5 TO 7 FEET IN THE OUTER WATERS. IN THE HARBOR,  
CONDITIONS LOOK TO REMAIN JUST SHY OF SMALL CRAFT ADVISORY  
CRITERIA.  
 
THURSDAY THROUGH MONDAY: WINDS/SEAS WILL IMPROVE THURSDAY AS THE  
PRESSURE GRADIENT AND COLD ADVECTION WANE, WITH THE OFFSHORE WATERS  
DROPPING BELOW ADVISORY LEVELS IN THE EARLY-MID AFTERNOON. NO OTHER  
SIGNIFICANT CONCERNS THEREAFTER THROUGH NEXT MONDAY.  
 

 
   
EQUIPMENT
 
 
THE KCLX RADAR IS OUT OF SERVICE UNTIL FURTHER NOTICE. REPAIRS  
ARE ONGOING. ADJACENT RADARS INCLUDE: KLTX, KCAE, KJGX, KVAX  
AND KJAX.  
 
THE DOWNTOWN CHARLESTON OBSERVATION SITE (CHLS1/KCXM) REMAINS  
OUT OF SERVICE UNTIL FURTHER NOTICE.  
 

 
   
CHS WATCHES/WARNINGS/ADVISORIES
 
 
GA...WIND CHILL ADVISORY FROM 4 AM TO 8 AM EST THURSDAY FOR  
GAZ116>119-137>141.  
SC...WIND CHILL ADVISORY FROM 4 AM TO 8 AM EST THURSDAY FOR  
SCZ048>052.  
MARINE...SMALL CRAFT ADVISORY UNTIL 7 AM EST THURSDAY FOR AMZ350-352.  
SMALL CRAFT ADVISORY UNTIL 7 AM EST THURSDAY FOR AMZ354.  
SMALL CRAFT ADVISORY UNTIL 1 PM EST THURSDAY FOR AMZ374.  
 

 
 

 
NEAR TERM...ECT  
SHORT TERM...RJB  
LONG TERM...  
AVIATION...ECT  
MARINE...ECT/RJB  
EQUIPMENT...  
 
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