788
FXUS62 KCHS 160642
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
142 AM EST TUE DEC 16 2025
SYNOPSIS
HIGH PRESSURE WILL PREVAIL TODAY THROUGH THURSDAY BEFORE A COLD
FRONT PUSHES OFFSHORE FRIDAY.
NEAR TERM /THROUGH TONIGHT/
PRIOR TO DAYBREAK: DRY HIGH PRESSURE WILL PREVAIL ACROSS THE AREA
THROUGH THE NIGHT, WHICH HAS ALREADY LED TO LIGHT/CALM WINDS UNDER
CLEAR SKIES, AND WILL CONTINUE TO SUPPORT A STRONG RADIATIONAL
COOLING SETUP INTO DAYBREAK. RECENT SFC OBSERVATIONS INDICATE TEMPS
ALREADY IN THE LOW-MID 20S AWAY FROM THE COASTAL CORRIDOR. ALTHOUGH
WINDS WILL REMAIN LIGHT/CALM FOR THE REMAINDER OF THE NIGHT, SFC
TEMPS SHOULD COOL ANOTHER FEW DEGREES, LEADING TO OVERNIGHT LOWS IN
THE UPPER TEENS/LOWER 20S INLAND AND MID-UPPER 20S CLOSER TO THE
COAST. TEMPS SHOULD REMAIN IN THE LOWER 30S ALONG THE BEACHES. THE
SETUP CONTINUES TO SUPPORT A COLD WEATHER ADVISORY UNTIL 9 AM FOR
MOST INLAND ZONES ACROSS SOUTHEAST SOUTH CAROLINA AND SOUTHEAST
GEORGIA.
TODAY: ALOFT, A NORTHWEST FLOW WILL PREVAIL BETWEEN A BROAD TROUGH
EXITING OFF THE NORTHEAST COAST AND A RIDGE EXPANDING FROM THE DEEP
SOUTH ACROSS THE SOUTHEAST. AT THE SFC, HIGH PRESSURE WILL PREVAIL
FOR THE DAY, BUT WILL GRADUALLY BECOME MORE CENTERED OFFSHORE BY THE
AFTERNOON, SUPPORTING A LIGHT WEST-SOUTHWESTERLY WIND UNDER A FULL
DAY OF SUNSHINE. THE DAY WILL START OFF CHILLY, BUT THE COMBINATION
OF A DRY DOWNSLOPE WIND ALOFT AND A LIGHT WEST-SOUTHWESTERLY WIND
UNDER CLEAR SKIES WILL HELP MODIFY THE AIRMASS AND LEAD TO
NOTICEABLY WARMER AFTERNOON TEMPS COMPARED TO THE PREVIOUS DAY. IN
GENERAL, HIGH TEMPS SHOULD RANGE IN THE MID-UPPER 50S (WARMEST
ACROSS SOUTHEAST GEORGIA). A FEW LOCATIONS COULD SEE TEMPS REACH 60
DEGREES ALONG THE ALTAMAHA RIVER IN SOUTHEAST GEORGIA. THESE TEMPS
ALONG WITH A DRY DOWNSLOPE PATTERN ALSO SUGGEST ANOTHER DAY WHERE
RELATIVE HUMIDITY VALUES DIP INTO THE 20-25% RANGE ACROSS AREAS WELL
INLAND DURING PEAK HEATING. HOWEVER, WINDS WILL REMAIN VERY LIGHT
THROUGHOUT THE DAY, LIMITING FIRE WEATHER CONCERNS LOCALLY.
TONIGHT: ALOFT, A WEAK RIDGE WILL BE PLACED DIRECTLY OVERHEAD WHILE
SFC HIGH PRESSURE CENTERED ACROSS THE WESTERN ATLANTIC EXTENDS WEST
ACROSS THE SOUTHEAST. ANY LIGHT WIND THAT HAS DEVELOPED DURING THE
DAYTIME WILL QUICKLY GO CALM AROUND SUNSET, SETTING UP THE STAGE FOR
RADIATIONAL COOLING EARLY. HOWEVER, AIRMASS MODIFICATION ALONG WITH
CLOUDS ARRIVING DURING THE SECOND HALF OF THE NIGHT WILL LIKELY
SUPPORT TEMPS ABOUT 10-15 DEGREES WARMER THAN THE PREVIOUS NIGHT. IN
GENERAL, LOWS SHOULD RANGE IN THE LOW-MID 30S INLAND TO LOW-MID 40S
CLOSER TO THE COAST.
SHORT TERM /WEDNESDAY THROUGH FRIDAY/
WEDNESDAY: A GRADUALLY MODERATING PATTERN WILL BE IN PLACE AS HIGH
PRESSURE SHIFTS OFFSHORE AND WEAK UPPER-LVL RIDGING BUILDS OVER THE
SOUTHEAST. LOW-LVL FLOW WILL VEER FROM NORTHERLY IN THE MORNING TO
WEST-SOUTHWESTERLY BY THE AFTERNOON, ALLOWING MODEST WAA TO DEVELOP.
THIS PATTERN WILL YIELD WARMING CONDITIONS AND THE FORECAST SHOULD
REMAIN RAIN-FREE WITH TEMPERATURES INTO THE LOW TO MID 60S WITH SOME
SPOTS REACHING IN THE UPPER 60S ACROSS EXTREME SOUTHEAST GEORGIA.
WHILE WINDS SHOULD BE GENERALLY LIGHT AND VARIABLE, IT'S POSSIBLE A
WEAK RESULTANT SEA BREEZE COULD DEVELOP NEAR THE BEACHES IN THE
AFTERNOON. THE COMBINATION OF MOSTLY CLOUDY SKIES AND SLIGHTLY
HIGHER DEWPOINTS SHOULD ALLOW TEMPERATURES TO STAY MILD WITH LOWS IN
THE MID TO UPPER 40S. THE ATMOSPHERE LOOKS TO REMAIN STABLE THROUGH
THE NIGHT WITH NO MEANINGFUL FORCING.
THURSDAY: LOW-LVL SOUTH-SOUTHWESTERLY FLOW WILL ADVECT WARM AND
HUMID AIR INTO THE REGION, YIELDING PWAT VALUES ~1.5 INCHES BY THE
AFTERNOON. MOSTLY CLOUDY SKIES WILL LIMIT INSOLATION, HOWEVER
THICKNESS VALUES WILL ALLOW HIGHS TO CLIMB INTO THE UPPER 60S TO LOW
70S WITH SLIGHTLY COOLER TEMPS. ALONG THE IMMEDIATE COASTLINE.
PRECIPITATION CHANCES WILL GRADUALLY INCREASE THROUGHOUT THE DAY AS
AN UPPER-LVL TROUGH ADVANCES EASTWARD TOWARDS THE REGION WITH AN
ASSOCIATED COLD FRONT. EXPECT SCATTERED SHOWERS TO DEVELOP AND
EXPAND FROM WEST TO EAST OVERNIGHT WITH THE HIGHEST CHANCE AFTER
MIDNIGHT. IT'S IMPORTANT TO NOTE THAT EVEN THOUGH OVERALL
INSTABILITY REMAINS LIMITED, THERE IS A SLIGHT CHANCE FOR
THUNDERSTORMS TO DEVELOP OVER SOUTHEAST GEORGIA LATE THURSDAY NIGHT.
RAINFALL AMOUNTS REMAIN LIGHT WITH LESS THAN 0.50 INCHES EXPECTED IN
THE SPAN OF 24 HRS. OVERNIGHT TEMPERATURES WILL REMAIN MILD DUE TO
THE OVERCAST SKIES WITH LOWS RANGING FROM LOW TO MID 50S.
FRIDAY: BROAD MID-LVL TROUGHING WILL EXTEND INTO FROM THE BLUEGRASS
REGION INTO THE DEEP SOUTH AS THE ASSOCIATED COLD FRONT PROGRESSES
EASTWARD TOWARDS THE REGION. IT'S POSSIBLE TO SEE SOME LIGHT SHOWERS
IN THE MORNING BEFORE THE COLD FRONT PASSES THROUGH. THERE HAS BEEN
A BIT OF UNCERTAINTY IN THE TIMING OF THE FRONT AMONGST GUIDANCE,
HOWEVER SOMETIME IN THE MORNING HOURS LOOKS REASONABLE. EXPECT HIGH
PRESSURE TO BUILD INTO THE REGION FROM THE WEST AFTERWARDS. SKIES
SHOULD GRADUALLY CLEAR THROUGHOUT THE DAY AND ALLOW TEMPERATURES TO
REACH INTO THE LOW TO MID 60S ACROSS SOUTHEAST SOUTH CAROLINA AND
MID TO UPPER 60S ACROSS SOUTHEAST GEORGIA. OVERNIGHT LOWS WILL BE A
BIT COOLER THAN THE PREVIOUS COUPLE NIGHTS WITH TEMPS. DIPPING INTO
THE LOW 30S ACROSS THE INTERIOR COUNTIES AND UPPER 30S TO LOW 40S
CLOSER TO THE COASTLINE.
LONG TERM /FRIDAY NIGHT THROUGH MONDAY/
EXPECT A RETURN OF COOL AND DRY CONDITIONS AS HIGH PRESSURE
CONTINUES TO BUILD INTO THE REGION. THIS PATTERN WILL YIELD MOSTLY
SUNNY SKIES, LIGHT WINDS, AND A COOL START TO THE MORNINGS.
TEMPERATURES WILL MODERATE BACK TO ABOVE NORMAL THROUGH EARLY NEXT
WEEK. THERE IS POTENTIAL FOR ANOTHER COLD FRONT TO APPROACH THE
REGION ON SUNDAY, HOWEVER CONFIDENCE REMAINS LOW WITH THE TIMING AND
IMPACTS OF THIS AT THE MOMENT.
AVIATION /06Z TUESDAY THROUGH SATURDAY/
VFR CONDITIONS WILL PREVAIL AT CHS/JZI/SAV TERMINALS THROUGH 06Z
WEDNESDAY.
EXTENDED AVIATION OUTLOOK: PERIODS OF MVFR POSSIBLE ON THURSDAY
NIGHT AS INCREASING CLOUD COVER AND SHOWERS MIGHT RESULT IN LOWER
CEILINGS AND VSBYS. CONDITIONS SHOULD IMPROVE ON FRIDAY BEHIND THE
PASSAGE OF THE COLD FRONT.
MARINE
PRIOR TO DAYBREAK: COOL HIGH PRESSURE WILL PREVAIL, SETTING UP A
WEAK PRESSURE GRADIENT ACROSS LOCAL WATERS AND NORTHERLY WIND NO
HIGHER THAN 10-15 KT (STRONGEST ACROSS OUTER GEORGIA WATERS). WINDS
AND SEAS WILL REMAIN BELOW SMALL CRAFT ADVISORY LEVELS FOR NEARSHORE
WATERS (SEAS 2-4 FT). THE EXCEPTION REMAINS ACROSS OUTER GEORGIA
WATERS, WHERE LINGERING 6 FT SEAS OCCUR FOR THE NEXT COUPLE HOURS. A
SMALL CRAFT ADVISORY HAS BEEN EXTENDED UNTIL 4 AM FOR THIS ZONE AS A
RESULT.
TODAY AND TONIGHT: HIGH PRESSURE WILL DOMINATE THE PATTERN, BECOMING
MORE CENTERED ACROSS THE WESTERN ATLANTIC DURING THE AFTERNOON, THEN
PERSISTING THROUGH THE NIGHT. WIND/SEAS ARE EXPECTED TO REMAIN WELL
BELOW SMALL CRAFT ADVISORY LEVELS THROUGH THE PERIOD, WITH A 10 KT
NORTHERLY WIND TODAY TURNING MORE NORTHEAST AND WEAKENING OVERNIGHT.
SEAS WILL ALSO SUBSIDE DURING THE PERIOD, FROM 2-5 FT EARLY TODAY TO
1-3 FT ACROSS NEARSHORE WATERS AND 3-4 FT ACROSS OUTER GEORGIA
WATERS TONIGHT.
WEDNESDAY THROUGH SATURDAY: SITUATED BETWEEN A WEAKENING HIGH
OFFSHORE AND A DEVELOPING LOW ACROSS THE CENTRAL CONUS, EXPECT THE
PRESSURE GRADIENT TO GRADUALLY TIGHTEN ACROSS THE LOCAL WATERS ON
WEDNESDAY AND THURSDAY. THE PERIOD OF LARGEST CONCERN REMAINS TO BE
ON THURSDAY NIGHT INTO FRIDAY AHEAD OF THE APPROACHING COLD FRONT.
SOUTHWESTERLY WINDS WILL BECOME ELEVATED WITH SPEEDS OF 15 TO 20 KTS
WITH GUSTS OF 25 KTS POSSIBLE. ALSO, EAST-SOUTHEASTERLY SWELL WILL
BUILD INTO THE WATERS WITH SEAS RANGING FROM 3 TO 5 FT WITH SOME 6
FOOTERS REACHING INTO NEARSHORE CHARLESTON AND OUTER GEORGIA WATERS.
SMALL CRAFT ADVISORIES WILL LIKELY BE NEEDED ON THURSDAY NIGHT INTO
FRIDAY.
CHS WATCHES/WARNINGS/ADVISORIES
GA...COLD WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR GAZ087-
088-099>101-115-116.
SC...COLD WEATHER ADVISORY UNTIL 9 AM EST THIS MORNING FOR SCZ040-
042>045-047.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EST EARLY THIS MORNING FOR
AMZ374.
NEAR TERM...DPB
SHORT TERM...DENNIS
LONG TERM...DENNIS
AVIATION...DENNIS/DPB
MARINE...DENNIS/DPB
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