266
FXUS62 KCHS 181158
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
658 AM EST THU DEC 18 2025
SYNOPSIS
A WARM FRONT WILL SHIFT NORTH ACROSS THE AREA TODAY BEFORE A
COLD FRONT ARRIVES TONIGHT. HIGH PRESSURE WILL THEN PREVAIL
DURING THE WEEKEND. ANOTHER COLD FRONT COULD SHIFT ACROSS THE
AREA MONDAY, BEFORE HIGH PRESSURE RETURNS AND PREVAILS INTO THE
MIDDLE OF NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
TODAY AND TONIGHT: ALOFT, A SOUTHWEST FLOW WILL BE IN PLACE TO
START THE DAY AHEAD OF A SOUTHERN STREAM SHORTWAVE TRACKING
ACROSS THE DEEP SOUTH AND NORTHERN GULF COAST REGION. AT THE
SFC, A COASTAL TROUGH IS ANTICIPATED TO SHIFT ONSHORE AS WARM
FRONT EARLY, EVENTUALLY LIFTING NORTH OF THE LOCAL AREA BY LATE
MORNING AND KEEPING THE REGION WARM-SECTORED THROUGH THE
AFTERNOON PRIOR TO A COLD FRONT ARRIVING TONIGHT. BREEZY SOUTH-
SOUTHWEST WINDS WILL HELP ADVECT DEEP MOISTURE INTO THE AREA
(PWATS APPROACHING 1.5 TO 1.75 INCHES) AND MILD AIR (HIGH TEMPS
IN THE UPPER 60S/LOWER 70S), SETTING THE STAGE FOR NUMEROUS TO
WIDESPREAD RAIN/SHOWERS AND EVEN A FEW EMBEDDED THUNDERSTORMS.
PRECIP COVERAGE APPEARS MOST WIDESPREAD LATE AFTERNOON AND EARLY
EVENING WHEN THE COMBINATION OF DEEP MOISTURE AND FORCING
(STRONG UPPER LVL JET, H5 VORT ENERGY AND ISENTROPIC LIFT) ALIGN
PRIOR TO THE COLD FRONT ARRIVING FROM THE WEST. THE FRONT LOOKS
QUITE PROGRESSIVE WITH A HIGH AMPLITUDE MID-UPPER LVL TROUGH
FORCING IT TO THE EASTERN SEABOARD AFTER MIDNIGHT TONIGHT.
EXPECT RAIN/SHOWERS AND PERHAPS A FEW EMBEDDED THUNDERSTORMS
(NON-SEVERE) TO PERSIST DURING EVENING AND OVERNIGHT HOURS
UNTIL FROPA OCCURS LATE, ALTHOUGH THE MID-UPPER LVL TROUGH
COULD SPAWN A FEW SHOWERS POST FRONT LATE NIGHT. TOTAL RAINFALL
AMOUNTS IN THE 1/2 TO 1 INCH RANGE SHOULD BE COMMON, HIGHEST
ALONG AND EAST OF THE I-95 CORRIDOR, PARTICULARLY NEAR THE
SOUTHEAST SOUTH CAROLINA COAST LATE DAY/EVENING. OVERNIGHT LOWS
REMAIN MILD DESPITE FROPA, GENERALLY IN THE LOW-MID 50S INLAND
TO UPPER 50S NEAR THE COAST.
LAKE WIND: LOW-LVL WIND FIELDS WILL STRENGTHEN ACROSS THE AREA TODAY
AS A COLD FRONT APPROACHES THE AREA OVERNIGHT. A WARM AIR ADVECTION
REGIME COULD LIMIT MIXING OF STRONGER WINDS ACROSS THE LAKE TODAY,
BUT EVENTUALLY LEAD TO GUSTS UPWARDS TO AROUND 25 KT TONIGHT. A LAKE
WIND ADVISORY COULD EVENTUALLY BE NEEDED LATE EVENING AND OVERNIGHT.
SHORT TERM /FRIDAY THROUGH SUNDAY/
FRIDAY: BROAD MID-LVL TROUGHING WILL EXTEND FROM THE OHIO RIVER
VALLEY INTO THE DEEP SOUTH AS AN ASSOCIATED COLD FRONT MARCHES
OFFSHORE BY MID TO LATE MORNING. A BAND OF WEAKENING STRATIFORM
PRECIPITATION WILL LIKELY BE PRESENT ALONG THE FRONTAL BOUNDARY IN
THE EARLY MORNING HOURS AS IT PASSES THROUGH THE REGION. THEREAFTER,
SKIES SHOULD QUICKLY CLEAR AS POST-FRONTAL CONDITIONS SHOULD LIMIT
FORCING AT THE SURFACE AND PROMOTE SUBSIDENCE. THIS WILL YIELD
TEMPERATURES IN THE LOW TO MID 60S ACROSS THE LOWCOUNTRY. OVERNIGHT
LOWS WILL BE A BIT COOLER THAN THE PREVIOUS NIGHT WITH TEMPERATURES
DROPPING INTO THE LOW 30S ACROSS THE INTERIOR COUNTIES AND UPPER 30S
TO LOW 40S CLOSER TO THE COASTLINE.
SATURDAY AND SUNDAY: A SHALLOW UPPER-LVL TROUGH COULD PASS OVER THE
EASTERN CONUS THIS WEEKEND WITHIN THE RETURN OF QUASI-ZONAL FLOW
ALOFT. AT THE SURFACE, HIGH PRESSURE WILL BE CENTERED ACROSS THE MID-
ATLANTIC AND WILL YIELD WARM AND DRY CONDITIONS ACROSS THE
SOUTHEAST. AS SUBSIDENCE CONTINUES TO ENVELOPE THE REGION, SKIES
WILL REMAIN MOSTLY CLEAR AND TEMPERATURES WILL MODERATE BACK TO NEAR
NORMAL. THIS IS NOTHING TO WRITE HOME ABOUT, BUT IT'S POSSIBLE A
WEAK SEABREEZE COULD DEVELOP ON SATURDAY AFTERNOON. SOME OF THE
RECENT MODEL GUIDANCE CONTINUES TO SIGNAL THAT ANOTHER COLD FRONT
COULD APPROACH THE REGION ON SUNDAY NIGHT AND WINDS WILL LIKELY
BECOME A BIT BREEZY AHEAD OF IT (ESP. IN THE EVENING AND INTO
OVERNIGHT). IT'S IMPORTANT TO NOTE THAT NO PRECIPITATION IS EXPECTED
WITH THIS FRONTAL PASSAGE. CONSIDERING THE ABSENCE OF CLOUDS IN THE
SKY THIS WEEKEND, STRONG RADIATIONAL COOLING WILL LIKELY BE THE MAIN
DRIVER OF THE OVERNIGHT LOWS WITH TEMPS. FALLING INTO THE UPPER 30S
TO LOW 40S.
LAKE WIND: SOUTHWESTERLY FLOW EXPECTED TO SURGE NEAR/BEHIND A
COLD FRONT THURSDAY NIGHT INTO EARLY FRIDAY MORNING, AND THEN
BECOME MORE WESTERLY BEHIND THE FRONT ON FRIDAY MID TO LATE
MORNING. THERE COULD BE A SHORT WINDOW OF TIME WHERE GUSTS COULD
BE REACH NEAR AND ABOVE 25 KNOTS ACROSS LAKE MOULTRIE, AND A
LAKE WIND ADVISORY COULD BE NEEDED.
LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/
EXPECT QUIET AND RAIN-FREE WEATHER THROUGH THE PERIOD AS BROAD UPPER-
LVL RIDGING DOMINATES THE FORECAST THROUGH THE MIDDLE OF THE WEEK.
TEMPERATURES ON MONDAY WILL BE A BIT COOLER THAN THE REST OF THE
WEEK WITH THE PASSAGE OF THE COLD FRONT, HOWEVER TEMPERATURES WILL
QUICKLY REBOUND AND REACH NEAR TO ABOVE NORMAL VALUES THEREAFTER.
AVIATION /12Z THURSDAY THROUGH MONDAY/
AT CHS/JZI, VFR CONDITIONS SHOULD PREVAIL THROUGH LATE MORNING, EVEN
WITH COASTAL SHOWERS SHIFTING ONSHORE AND IMPACTING THE TERMINALS.
TEMPO MVFR CONDITIONS ARE ANTICIPATED BETWEEN 18-22Z AS RAIN AND/OR
SHOWER ACTIVITY INCREASES THIS AFTERNOON. GUSTY WINDS TO AROUND 20
KT COULD ALSO ACCOMPANY PRECIP ACTIVITY. THE BULK OF RAIN/SHOWERS
AND POSSIBLY A THUNDERSTORM COME BETWEEN 22Z AND 06Z TONIGHT, WHICH
LIKELY LEAD TO ADDITIONAL ROUNDS OF MVFR CONDITIONS LATE AFTERNOON
AND DURING EVENING HOURS. GUIDANCE HAS COME IN QUITE A BIT STRONGER
WITH GUSTY WINDS AND IFR CIGS WITH FROPA OVERNIGHT, THUS HAVE BEEN
ADDED BETWEEN 04-12Z FRIDAY. PRIOR TO THE GUSTY WINDS, LLWS IS
POSSIBLE LATE AFTERNOON/EVENING AS WELL.
AT SAV, VFR CONDITIONS PREVAIL DURING THE NEXT COUPLE HOURS WHILE
LIGHT RAIN/SHOWER ACTIVITY ASSOCIATED WITH A COASTAL SHIFTS ONSHORE
ALONG THE GEORGIA COAST. MVFR CIGS PREVAIL LATE MORNING INTO EARLY
AFTERNOON WITH LIGHT/MODERATE RAINS ANTICIPATED. THERE COULD BE A
PERIOD OF VFR CONDITIONS LATE DAY, BUT CONDITIONS WILL LIKELY LOWER
TO MVFR EARLY EVENING, THEN FOLLOWED BY EVEN LOWER CONDITIONS AFTER
04Z TONIGHT. GUIDANCE HAS COME IN QUITE A BIT STRONGER WITH GUSTY
WINDS AND IFR CIGS WITH FROPA OVERNIGHT, THUS HAVE BEEN ADDED
BETWEEN 04-12Z FRIDAY. PRIOR TO THE GUSTY WINDS, LLWS IS POSSIBLE
DURING EVENING HOURS AS WELL.
EXTENDED AVIATION OUTLOOK: PERIODS OF MVFR POSSIBLE FRIDAY MORNING
AS LIGHT SHOWERS MIGHT RESULT IN LOWER CEILINGS AND VSBYS. HOWEVER,
CONDITIONS SHOULD RAPIDLY IMPROVE IN THE LATE MORNING AS THE FRONT
PUSHES OFFSHORE.
MARINE
TODAY AND TONIGHT: A WEAK COASTAL TROUGH WILL SHIFT ONSHORE EARLY,
THEN LIFT NORTH AS A WARM FRONT EARLY TO MID MORNING. WINDS SHOULD
BECOME MORE SOUTHERLY BEHIND THIS FEATURE, GRADUALLY INCREASING
THROUGHOUT THE DAY AS THE PRESSURE GRADIENT SLOWLY TIGHTENS WELL IN
ADVANCE OF A COLD FRONT ARRIVING DURING THE SECOND HALF OF THE
NIGHT. ALTHOUGH WIND FIELDS INCREASE THROUGHOUT THE DAY, LOW-LVL
MIXING COULD BE AN ISSUE EARLY ON WITHIN A WARM AIR ADVECTION
REGIME, BUT WIND SPEEDS SHOULD GRADUALLY TOP OUT IN THE 15-20 KT
RANGE BY LATE DAY. ADDITIONALLY, SOME GUIDANCE SUGGESTS A WINDOW OF
OPPORTUNITY FOR SEA FOG TO DEVELOP LATE AFTERNOON/EARLY EVENING AS
SFC WINDS BECOME MORE PARALLEL TO THE COAST AND SFC DEWPTS SURGE
INTO THE LOWER 60S OVER SLIGHTLY COOLER WATERS. CHANCES APPEAR
HIGHEST ACROSS NEARSHORE WATERS ALONG AND SOUTH OF EDISTO ISLAND, SC
TO THE ALTAMAHA RIVER, GA. HOWEVER, WINDS DO PICK UP SPEED DURING
THIS TIME, WHICH SHOULD LIMIT THE POTENTIAL.
SEAS WILL BUILD TODAY, REACHING 6 FT ACROSS OUTER GEORGIA WATERS
LATE AFTERNOON, BUT EVEN MORE LIKELY EARLY EVENING (INCLUDING OFF
THE CHARLESTON COUNTY COAST). GIVEN THE ARRIVAL OF LARGER SEAS,
SMALL CRAFT ADVISORIES HAVE BEEN ISSUED FOR OUTER GEORGIA WATERS
STARTING LATE AFTERNOON AND ACROSS NORTHERN SOUTH CAROLINA WATERS
OFF THE CHARLESTON COUNTY COAST STARTING STARTING EARLY EVENING.
SOUTHERN SOUTH CAROLINA NEARSHORE WATERS ALSO FEATURES A SMALL CRAFT
ADVISORY TONIGHT, ALTHOUGH WITH A LATER START TIME BASED ON THE
ARRIVAL OF LARGER SEAS. SOUTHWEST WINDS COULD TOP OUT NEAR 25-30 KT
ACROSS ZONES ALREADY INCLUDED IN SMALL CRAFT ADVISORIES OVERNIGHT
AND SHOULD PERSIST INTO EARLY FRIDAY. SEAS SHOULD ALSO BUILD TO 6-8
FT, LARGEST ACROSS OUTER GEORGIA WATERS AND NORTHERN SOUTH CAROLINA
NEARSHORE WATERS. A BRIEF PERIOD OF SMALL CRAFT ADVISORIES COULD
EVENTUALLY BE NEEDED ACROSS THE CHARLESTON HARBOR AND NEARSHORE
GEORGIA WATERS AS WELL, BUT THE EVENT WOULD BE BASED ON MORE
MARGINAL CONDITIONS AND WILL NEED TO BE REEVALUATED LATER TODAY.
FRIDAY THROUGH MONDAY: EXPECT A COLD FRONT TO PASS OVER THE LOCAL
WATERS MID TO LATE MORNING AND YIELD WEST-SOUTHWESTERLY WINDS AT 15
TO 20 KTS WITH GUSTS UP TO 25 KTS. ALSO, A WEAKENING BAND OF SHOWERS
ASSOCIATED WITH THE FRONT COULD PASS THROUGH AS WELL EARLY FRIDAY
MORNING. BY FRIDAY AFTERNOON, WINDS SHOULD SHIFT MORE NORTHWESTERLY
AND WIND SPEEDS SHOULD DECREASE TO 10 TO 15 KTS. EAST-SOUTHEASTERLY
SWELL CONTINUES TO MIX INTO THE WATERS WITH SEAS RANGING FROM 6 TO 8
FT ON FRIDAY MORNING, AND THEN QUICKLY TAPER BACK TO 4 TO 6 FT BY
THE AFTERNOON. THEREAFTER, EXPECT SEAS TO RANGE 2 TO 3 FT OVER THE
WEEKEND, BEFORE ANOTHER SWELL TRIES TO SETTLE INTO THE WATERS ON
MONDAY. SMALL CRAFT ADVISORIES HAVE BEEN ISSUED FOR NEARSHORE SOUTH
CAROLINA WATERS AND THE OUTER GEORGIA WATERS UNTIL FRIDAY EVENING
GIVEN THE ELEVATED MARINE CONDITIONS.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 7 PM EST FRIDAY
FOR AMZ350.
SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 1 PM EST
FRIDAY FOR AMZ352.
SMALL CRAFT ADVISORY FROM 4 PM THIS AFTERNOON TO 7 PM EST
FRIDAY FOR AMZ374.
NEAR TERM...DPB
SHORT TERM...DENNIS
LONG TERM...DENNIS
AVIATION...DENNIS/DPB
MARINE...DENNIS/DPB
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