305
FXUS62 KCHS 150854
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
354 AM EST MON DEC 15 2025
SYNOPSIS
BITTER COLD CONDITIONS WILL PREVAIL TODAY THROUGH TUESDAY. DRY
HIGH PRESSURE REMAINS IN CONTROL THROUGH THURSDAY BEFORE THE
NEXT COLD FRONT IMPACTS THE AREA FRIDAY.
NEAR TERM /THROUGH TONIGHT/
PRIOR TO DAYBREAK: ARCTIC HIGH PRESSURE WILL CONTINUE TO BUILD
ACROSS THE REGION, RESULTING IN DRY AND BITTER COLD CONDITIONS
PRIOR TO SUNRISE. TEMPERATURES DIPPING INTO THE LOW-MID 20S
ALONG WITH NORTHERLY WINDS GUSTING UPWARDS TO 15-25 MPH
(STRONGEST NEAR THE COAST) WILL SUPPORT WIND CHILL VALUES IN THE
11-20 DEGREE RANGE AND THE CONTINUATION OF A COLD WEATHER
ADVISORY FOR ALL AREAS UNTIL 10 AM THIS MORNING. COLDEST WIND
CHILL VALUES ARE EXPECTED PRIOR TO SUNRISE AND BEFORE WINDS
START TO WEAKEN. A FEW LOCATIONS COULD SEE WIND CHILL VALUES DIP
TO AROUND 10 DEGREES ACROSS THE TRI-COUNTY AREA AND PERHAPS
SOUTH ALONG THE I-95 CORRIDOR, BUT COVERAGE AND DURATION REMAIN
QUITE SHORT AND STILL REPRESENTATIVE UNDER A COLD WEATHER
ADVISORY.
LAKE WIND: STRONG COLD AIR ADVECTION ASSOCIATED WITH BUILDING HIGH
PRESSURE POST COLD FRONT WILL CONTINUE TO SUPPORT WIND GUSTS
AROUND 25 KT DURING THE NEXT 1-2 HOURS. A LAKE WIND ADVISORY
REMAINS IN EFFECT ACROSS LAKE MOULTRIE UNTIL 6 AM.
TODAY: ALOFT, A BROAD TROUGH WILL PREVAIL ACROSS THE EAST CONUS,
PLACING A NORTHWEST DOWNSLOPE WIND ACROSS THE LOCAL AREA. AT THE
SFC, COLD HIGH PRESSURE WILL CONTINUE TO BUILD ACROSS THE SOUTHEAST
AND PREVAIL THROUGH THE DAY. THE PATTERN SUPPORTS DRY CONDITIONS FOR
ALL AREAS WITH EVEN SOME RH VALUES TOUCHING 20-25% ACROSS INLAND
AREAS DURING THE AFTERNOON. HOWEVER, THE PRESSURE GRADIENT WILL
WEAKEN CONSIDERABLY DURING MAXIMUM DAYTIME HEATING, SUPPORTING A
DOWNWARD TREND IN WIND SPEEDS, GENERALLY TO 5-10 MPH OR LESS AWAY
FROM THE COAST, THUS LIMITING FIRE WEATHER CONCERNS FOR THE DAY.
STRONG COLD AIR ADVECTION OCCURRING WITH A NORTHERLY SFC WIND WILL
ALSO OFFSET WARMING ASSOCIATED WITH THE DOWNSLOPE PATTERN AND A FULL
DAY OF SUNSHINE, SUPPORTING HIGH TEMPS ONLY IN THE LOW-MID 40S. A
FEW TEMPS COULD ONLY PEAK IN THE UPPER 30S ACROSS NORTHERN BERKELEY
COUNTY.
TONIGHT: DRY HIGH PRESSURE WILL SETTLE ACROSS THE SOUTHEAST UNITED
STATES, SUPPORTING STRONG RADIATIONAL COOLING CONDITIONS LOCALLY
UNDER CLEAR SKIES DURING THE NIGHT. THE MAIN ISSUE WILL BE COLD
TEMPERATURES. SFC WINDS ARE LIKELY TO DECOUPLE EARLY, LEADING TO A
LIGHT/CALM WIND FOR MOST AREAS AWAY FROM THE BEACHES. ALTHOUGH TEMPS
ARE LIKELY TO COOL INTO THE LOW-MID 20S ACROSS INLAND ZONES, A CALM
WIND SHOULD DO LITTLE IN THE WAY TO LOWER WIND CHILL TEMPERATURES
BELOW 20 DEGREES, AT LEAST FOR A MAJORITY OF THE AREA. A FEW SPOTS
WELL INLAND, MAINLY FROM A STRETCH ACROSS WESTERN DORCHESTER COUNTY,
SC TO NORTHERN TATTNALL COUNTY, GA, COULD EXPERIENCE TEMPERATURES
NEAR 20 DEGREES BRIEFLY, LIMITING THE NEED FOR A COLD WEATHER
ADVISORY LATE, BUT TRENDS WILL CONTINUE TO BE MONITORED FOR ANY
SLIGHTLY COLDER SCENARIO. SHOULD TEMPERATURES TREND COLDER THAN
EXPECTED, A COLD WEATHER ADVISORY COULD BECOME NECESSARY FOR AREAS
WELL INLAND.
SHORT TERM /TUESDAY THROUGH THURSDAY/
OVERVIEW: BITTER COLD TEMPERATURES CONTINUE THROUGH TUESDAY MORNING,
THEN BEGIN TO MODERATE BY MID WEEK.
TUESDAY AND WEDNESDAY: AS AN UPPER-LVL TROUGH GRADUALLY SHARPENS
OVER THE ATLANTIC, QUASI-ZONAL FLOW WILL DOMINATE THE FORECAST AT
THE SURFACE. MARGINAL MOISTURE WILL BE AVAILABLE WITH PWAT VALUES
BELOW 0.8 INCHES, THUS NOT MUCH EXPECTED IN TERMS OF PRECIPITATION.
EXPECT LOWS TO REMAIN CHILLY ON TUESDAY NIGHT WITH TEMPERATURES IN
THE LOW TO MID 30S (WITH LOW 40S NEAR THE BEACHES) AS POST-FROPA
CONDITIONS REMAIN IN PLAY. TEMPERATURES WILL LIKELY REACH TO NEAR TO
SLIGHTLY ABOVE NORMAL BY WEDNESDAY.
THURSDAY: EXPECT THIS QUASI-ZONAL FLOW PATTERN TO QUICKLY CHANGE AS
AN UPPER-LVL TROUGH TRACKS EASTWARD INTO THE CENTRAL CONUS ON
THURSDAY. AN ASSOCIATED COLD FRONT WILL ALSO TRACK TOWARDS THE
REGION AS MOISTURE SLOWLY ADVECTS INTO THE SOUTHEAST. THIS SYSTEM
WILL ALLOW FOR PRECIP. CHANCES TO RETURN AND FORECAST NOTES 20-30%
POPS. THIS FRONT WILL APPROACH THE REGION RATHER QUICKLY ON THURSDAY
NIGHT. ENSEMBLE GUIDANCE CONTINUES TO SUGGEST THAT RAINFALL WILL
REMAIN LIMITED WITH LESS THAN 0.50 INCHES EXPECTED. SOUTHEASTERLY
WINDS WILL INCREASE IN THE AFTERNOON AHEAD OF THE APPROACHING FRONT
AND REMAIN ELEVATED THROUGHOUT THE NIGHT. THERE IS STILL SOME
UNCERTAINTY REGARDING THE TIMING OF THE FRONT, THUS THERE COULD BE
SMALL CHANGES WITH THIS IN THE NEXT COUPLE FORECAST UPDATES.
LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/
THE COLD FRONT SHOULD PASS THROUGH THE REGION SOMETIME ON FRI.
MORNING, AND THEN HIGH PRESSURE SHOULD BUILD IN FROM THE NORTHEAST.
IT APPEARS THERE WON'T BE MUCH IMPACT TO THE AREA WITH THIS SYSTEM
OTHER THAN A WIND SHIFT. TEMPERATURES WILL HOP ON A WARMING TREND TO
ABOVE NORMAL THROUGH THE WEEKEND AS UPPER-LVL FLOW REVERTS BACK TO
ZONAL. THERE IS SOME HINTING THAT ANOTHER COLD FRONT COULD APPROACH
THE REGION LATE IN THE PERIOD ON SUNDAY, HOWEVER GUIDANCE CLUSTERING
REMAINS SCATTERED AND CONFIDENCE REGARDING IMPACTS REMAINS LOW AT
THIS TIME.
AVIATION /08Z MONDAY THROUGH FRIDAY/
VFR CONDITIONS WILL PREVAIL AT CHS/JZI/SAV TERMINALS THROUGH 06Z
TUESDAY. HOWEVER, GUSTY NORTH/NORTHEAST WINDS (15-25 KT) ARE
EXPECTED AT ALL TERMINALS FOR MUCH OF TONIGHT, BEFORE TRENDING
WEAKER POST DAYBREAK THIS MORNING, THEN REMAINING AROUND 10 KT OR
LESS FOR THE REST OF THE DAY. LIGHT/CALM WINDS ARE EXPECTED AT ALL
TERMINALS BY AROUND 00Z TUESDAY TONIGHT.
EXTENDED AVIATION OUTLOOK: VFR CONDITIONS PREVAIL FOR KCHS, KJZI AND
KSAV THROUGH MID-WEEK.
MARINE
PRIOR TO DAYBREAK: STRONG COLD AIR ADVECTION ASSOCIATED WITH
BUILDING HIGH PRESSURE POST FRONT WILL CONTINUE TO SUPPORT NORTH-
NORTHEAST WINDS GUSTING UPWARDS TO 25-35 KT (STRONGEST OUTSIDE THE
CHARLESTON HARBOR). HOWEVER, THE PRESSURE GRADIENT WILL BE ON A
WEAKENING TREND AROUND DAYBREAK. GALE WARNINGS WILL CONTINUE ACROSS
ALL LOCAL WATERS, WHILE A SMALL CRAFT ADVISORY REMAINS IN EFFECT FOR
THE CHARLESTON HARBOR. SEAS SHOULD BUILD UP TO 5-8 FT ACROSS
NEARSHORE WATERS (LARGEST NEAR 20 NM OF THE CHARLESTON COUNTY COAST)
TO 7-10 FT ACROSS OUTER GEORGIA WATERS.
TODAY AND TONIGHT: COLD HIGH PRESSURE WILL CONTINUE TO SPREAD ACROSS
THE REGION, LEADING TO GUSTY WIND CONDITIONS ACROSS ALL WATERS
DURING EARLY-MID MORNING HOURS. GALE WARNINGS LIKELY COME TO AN END
SHORTLY AFTER DAYBREAK AND BECOME REPLACED WITH SMALL CRAFT
ADVISORIES FOR A FEW HOURS AS WINDS GRADUALLY TREND LOWER IN
RESPONSE TO THE PRESSURE GRADIENT BECOMING MUCH WEAKER BY THE
AFTERNOON. WINDS/SEAS WILL LIKELY DECREASE/SUBSIDE TO BELOW SMALL
CRAFT ADVISORY LEVELS FOR NEARSHORE WATERS BY EARLY AFTERNOON (MID-
LATE MORNING FOR THE CHARLESTON HARBOR), BUT A SMALL CRAFT ADVISORY
WILL LIKELY REMAIN IN EFFECT ACROSS OUTER GEORGIA WATERS THROUGH THE
EVENING. AFTER MIDNIGHT, CONDITIONS BECOME QUIET WITH HIGH PRESSURE
DIRECTLY ACROSS THE SOUTHEAST. NORTH/NORTHEAST WINDS SHOULD LOWER TO
AROUND 10 KT OR LESS WHILE SEAS SUBSIDE TO 3-5 FT.
TUESDAY THROUGH FRIDAY: ELEVATED SEAS WILL CONTINUE TAPER BACK AS
THE SWELL RECEDES BACK OUT TO THE ATLANTIC. MARINE CONDITIONS WILL
REMAIN BENIGN ON TUESDAY AND WEDNESDAY AS HIGH PRESSURE SITUATES
ITSELF ACROSS THE LOCAL WATERS. A COASTAL TROUGH COULD DEVELOP OVER
THE NEARSHORE WATERS ON THURSDAY AS AN AFOREMENTIONED COLD FRONT
APPROACHES. THIS MIGHT ALLOW FOR A SHORT-LIVED SWELL TO TAKE PLACE
ON FRIDAY, HOWEVER IT LOOKS LIKE IT WILL REMAIN BELOW SMALL CRAFT
ADVISORY THRESHOLDS. WINDS WILL LIKELY INCREASE AHEAD OF THE FRONTAL
PASSAGE ON THURSDAY, BUT AGAIN, NOTHING TO WRITE HOME ABOUT.
CLIMATE
RECORD LOW TEMPERATURES:
DECEMBER 15:
KCHS: 15/1962
KCXM: 23/1943
KSAV: 19/1962
RECORD LOW MAXIMUM TEMPERATURES:
DECEMBER 15:
KCHS: 39/1943
KCXM: 38/1904
KSAV: 38/1904
CHS WATCHES/WARNINGS/ADVISORIES
GA...COLD WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR GAZ087-
088-099>101-114>119-137>141.
SC...COLD WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR SCZ040-
042>045-047>052.
LAKE WIND ADVISORY UNTIL 6 AM EST EARLY THIS MORNING FOR
SCZ045.
MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EST THIS MORNING FOR AMZ330.
GALE WARNING UNTIL 7 AM EST THIS MORNING FOR AMZ350-352-354-
374.
NEAR TERM...DPB
SHORT TERM...DENNIS
LONG TERM...DENNIS
AVIATION...DENNIS/DPB
MARINE...DENNIS/DPB
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