938  
FXUS62 KCHS 162249  
AFDCHS  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE CHARLESTON SC  
549 PM EST WED JAN 16 2019  
   
SYNOPSIS
 
 
DRY HIGH PRESSURE WILL BUILD FROM THE WEST AND PREVAIL INTO  
THURSDAY. A WEAK UPPER LEVEL DISTURBANCE WILL MOVE THROUGH  
THURSDAY NIGHT. A STRONGER STORM SYSTEM WILL THEN IMPACT THE  
AREA SATURDAY NIGHT AND SUNDAY.  
 

 
   
NEAR TERM /UNTIL 6 AM THURSDAY MORNING/
 
 
FOR THE EARLY EVENING UPDATE WE HAVE EXPANDED THE RANGE OF  
MINIMUM TEMPS A LITTLE BIT MORE, BASED ON EXCELLENT RADIATIONAL  
COOLING INLAND AND JUST ENOUGH MIXING ALONG THE COAST TO OCCUR.  
THIS WILL PRODUCE SOME LOWS AT OR BELOW FREEZING ALONG PARTS OF  
THE COLDEST RURAL LOCATIONS OF OUR NORTHWEST TIER. OTHERWISE  
VERY FEW CHANGES REQUIRED AT THIS TIME.  
 
PREVIOUS DISCUSSION...  
ALOFT, SEMI-ZONAL FLOW WILL PERSIST OVER THE AREA. AT THE  
SURFACE, BROAD HIGH PRESSURE WILL SPREAD ACROSS THE EAST COAST,  
WITH ITS CENTER BECOMING LOCATED OVER THE GREAT LAKES REGION  
LATE. DRY WEATHER WILL PREVAIL. SKIES SHOULD BE MOSTLY CLEAR  
WITH SOME THIN CIRRUS POSSIBLE LATE. THIS COMBINED WITH CALM  
WINDS OVERNIGHT WILL ALLOW GOOD RADIATIONAL COOLING. LOWS SHOULD  
FALL INTO THE MID 30S INLAND AND NEAR 40 DEGREES AT THE  
IMMEDIATE COAST.  
 

 
   
SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/
 
 
SURFACE HIGH PRESSURE OVER THE EASTERN UNITED STATES WILL  
GRADUALLY SHIFT TO THE EAST THROUGH SATURDAY. A WEAK UPPER LEVEL  
DISTURBANCE WILL BRING A COLD FRONT THROUGH THE AREA THURSDAY  
NIGHT. MOISTURE RETURN AHEAD OF THIS WAVE WILL BE QUITE LIMITED  
AND THE QUASI-ZONAL FLOW ALOFT WILL LIMIT UPWARD VERTICAL  
MOTION. THEREFORE WE ONLY SHOW ISOLATED SHOWERS MOVING THROUGH  
FAR NORTHERN SC ZONES THURSDAY NIGHT. STRENGTHENING SOUTHERLY  
FLOW THURSDAY INTO FRIDAY WILL BRING WARMING TEMPERATURES WITH  
HIGHS REACHING THE MIDDLE 60S BY FRIDAY.  
 
AN UPPER TROUGH WILL MOVE OUT OF THE CENTRAL UNITED STATES ON  
SATURDAY WITH A STRONG COLD FRONT APPROACHING THE AREA LATE IN  
THE DAY SATURDAY. MOST OF THE ASSOCIATED PRECIPITATION WILL  
REMAIN WEST OF THE AREA THROUGH SUNSET. HOWEVER, DESPITE  
EXTENSIVE CLOUD COVER, CONTINUED WARM ADVECTION WILL RESULT IN  
HIGH TEMPS IN THE LOW TO MIDDLE 70S.  
 

 
   
LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/
 
 
MODERATE FORECAST CONFIDENCE MOST OF THE PERIOD. THERE IS MORE MODEL  
AGREEMENT NOW THAT A COLD FRONT WILL LIKELY MOVE THROUGH FROM THE  
WEST SATURDAY NIGHT INTO EARLY SUNDAY, WITH MUCH COLDER HIGH  
PRESSURE BUILDING IN THEREAFTER THROUGH EARLY NEXT WEEK. BY THE END  
OF THE PERIOD A COASTAL TROUGH AND A POSSIBLE LOW PRESSURE SYSTEM  
COULD BRING SOME RAIN BACK INTO THE FORECAST BUT CONFIDENCE IS MUCH  
LOWER TOWARD THE MIDDLE OF NEXT WEEK. MOST LOCALES SHOULD SEE A HALF  
INCH TO MAYBE 1 INCH OF RAIN THROUGH THE PERIOD, WITH MOST OF THE  
RAIN COMING OVER THE WEEKEND. ALTHOUGH DEEP LAYER SHEAR IS STRONG WE  
DON'T SEE A LOT OF INSTABILITY SO NOT OVERLY CONCERNED ABOUT THE  
SEVERE THUNDERSTORM THREAT AT THIS POINT AND IN FACT WE DON'T EVEN  
HAVE ANY MENTION OF THUNDERSTORMS. IT WILL ALSO BE BREEZY SUNDAY  
INTO EARLY MONDAY AND A LAKE WIND ADVISORY MAY BE NEEDED FOR LAKE  
MOULTRIE.  
 
MOST, IF NOT ALL, LOCALES SHOULD BE BELOW FREEZING MONDAY MORNING  
WITH INLAND AREAS IN THE MID TO UPPER 20S AND WIND CHILLS NEAR 20  
DEGREES. IT'S NOT OUT OF THE QUESTION THAT COASTAL AREAS REACH WIND  
CHILL ADVISORY LEVELS OF 15 DEGREES. HIGHS MONDAY SHOULD ONLY RANGE  
FROM AROUND 40 NEAR THE SANTEE RIVER TO 50 NEAR THE ALTAMAHA RIVER.  
TEMPERATURES MONDAY NIGHT ARE A BIT TRICKY AS MUCH DEPENDS ON HOW  
MUCH A COASTAL TROUGH AND HIGH CLOUDS COME INTO PLAY BUT INLAND  
AREAS SHOULD GET BACK BELOW FREEZING AGAIN. THEREAFTER TEMPERATURES  
WILL MODIFY INTO MID WEEK TO NEAR OR ABOVE NORMAL LEVELS.  
 

 
   
AVIATION /00Z THURSDAY THROUGH MONDAY/
 
 
00Z TAFS: VFR.  
 
EXTENDED AVIATION OUTLOOK: RESTRICTIONS EXPECTED SATURDAY NIGHT  
INTO EARLY SUNDAY, LIKELY IFR OR WORSE AT TIMES. ALSO,  
BREEZY/GUSTY CONDITIONS ARE EXPECTED LATER SATURDAY THROUGH AT  
LEAST SUNDAY NIGHT.  
 

 
   
MARINE
 
 
TONIGHT: HIGH PRESSURE OVER THE REGION WILL SUPPORT VARYING WINDS  
AROUND 5 KT. SEAS WILL BE NO MORE THAN 1 OR 2 FT, EXCEPT FOR  
SOME 3 FOOTERS BEYOND 50 NM OFFSHORE.  
 
EXTENDED MARINE: NO SIGNIFICANT CONCERNS THROUGH SATURDAY BUT  
CONDITIONS WILL BE DETERIORATING SIGNIFICANTLY SATURDAY NIGHT  
AND SUNDAY AS A STRONG COLD FRONT AFFECTS THE AREA WITH SOME  
HEAVY SHOWERS AND POSSIBLE THUNDERSTORMS (MAINLY NEAR THE GULF  
STREAM). WINDS COULD EVEN GUST NEAR GALE FORCE ACROSS THE GA  
WATERS BEYOND 20 NM. OTHERWISE, SMALL CRAFT ADVISORIES ARE  
LIKELY FOR THE ENTIRE AREA. SHOULD SEE IMPROVING CONDITIONS  
MONDAY AS WINDS TURN OFFSHORE AND DIMINISH WITH THE WEAKENING  
COLD AIR ADVECTION.  
 

 
   
TIDES/COASTAL FLOODING
 
 
COASTAL FLOODING: ASTRONOMICAL TIDE LEVELS WILL BE HIGH EARLY NEXT  
WEEK AND STRONG NORTH/NORTHEAST WINDS WILL HELP CONTRIBUTE TO EVEN  
HIGHER LEVELS WHICH COULD LEAD TO MINOR SALTWATER FLOODING  
AROUND HIGH TIDE. THUS, COASTAL FLOOD ADVISORIES WILL BE  
POSSIBLE.  
 

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

 
 

 
NEAR TERM...  
SHORT TERM...JRL  
LONG TERM...RJB  
AVIATION...  
MARINE...  
TIDES/COASTAL FLOODING...  
 
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