033
FXUS62 KCHS 281025
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
525 AM EST SUN DEC 28 2025
SYNOPSIS
A WEAK COLD FRONT WILL BRIEFLY STALL NEAR THE SAVANNAH RIVER
THIS MORNING BEFORE LIFTING NORTH THIS AFTERNOON. A COLD FRONT
WILL MOVE THROUGH THE AREA MONDAY WITH HIGH PRESSURE PREVAILING
FOR THE REST OF THE WEEK.
NEAR TERM /THROUGH TONIGHT/
TODAY: THE UPPER-LEVEL RIDGE AXIS WILL PASS OVER THE REGION
TODAY. A WEAK BACKDOOR COLD FONT WILL CONTINUE TO SINK SOUTH
EARLY THIS MORNING AND WILL LIKELY BECOME HUNG UP NEAR THE
SAVANNAH RIVER BY DAYBREAK. THE FRONT IS EXPECTED TO LIFT SLOWLY
BACK TO THE NORTH AS A WARM FRONT LATER IN THE DAY AS SURFACE
HIGH PRESSURE PROPAGATES TO THE SOUTHEAST AND WELL OFFSHORE OF
THE SOUTHEAST U.S. COAST. SOME SHALLOW GROUND FOG COULD POOL
ALONG THE SHALLOW FRONT ITSELF AND MAY RESULT IN A BAND OF LOWER
VISIBILITIES (ROUGHLY 3- 5SM) ACROSS FAR SOUTHERN SOUTH
CAROLINA AS DAYBREAK APPROACHES. IN ADDITION, WIDESPREAD DENSE
FOG DEVELOPING OVER THE FLORIDA PANHANDLE AND THE SUWANNEE
VALLEY IS EXPECTED TO EXPAND ACROSS FAR SOUTHEAST GEORGIA OVER
THE NEXT FEW HOURS, POSSIBLY OOZING NORTH TO NEAR THE ALTAMAHA
RIVER RIGHT AROUND SUNRISE. THE RISK FOR DENSE FOG LOOKS GREATEST
SOUTH OF THE ALTAMAHA RIVER, BUT IT COULD GET CLOSE. WEAK
ISENTROPIC LIFT NOTED ALONG THE 295-300K SURFACES COULD SPARK
A FEW SHOWERS IN THE VICINITY OF THE NORTHWARD MOVING WARM
FRONT LATER TODAY. THE RISK FOR SOME VERY LIGHT QPF LOOKS
HIGHEST ACROSS THE CHARLESTON TRI-COUNTY AREA. POPS AROUND 20%
WERE INTRODUCED TO ACCOUNT FOR THIS. HIGHS TODAY WILL RANGE
FROM THE LOWER 70S OVER SOUTHEAST SOUTH CAROLINA TO THE MID 70S
ACROSS SOUTHEAST GEORGIA. THERE ARE SOME SIGNALS THAT SUGGEST A
4000-6000 FT CLOUD DECK MAY END UP A BIT THICKER IN GEORGIA
WHICH MAY LIMIT HIGHS THERE A BIT. WHILE SOME STATISTICAL DATA
SUPPORT SLIGHTLY COOLER AFTERNOON HIGHS THAN WHAT THE 28/01 NBM
IS HIGHLIGHTING, THE UNKNOWNS ABOUT CLOUD COVER AND POSSIBLE
BREAKS ALLOWING FOR PERIODS OF GREATER INSOLATION NECESSITATE
LIMITING ANY SIGNIFICANT DEVIATIONS FROM THE NBM AT THIS TIME.
TONIGHT: THE AREA WILL BE FIRMLY IN THE WARM SECTOR AS A COLD
FRONT APPROACHES FROM THE WEST. INCREASING WIND FIELDS AND WEAK
WARM AIR ADVECTION WILL YIELD A FAIRLY WARM NIGHT WITH LOWS ONLY
DROPPING INTO THE UPPER 50S TO AROUND 60 FOR MOST AREAS.
CONDITIONS LOOKS SOMEWHAT FAVORABLE FOR THE DEVELOPMENT OF SEA
FOG OVER THE COASTAL WATERS OVERNIGHT. IT IS UNCLEAR HOW
WIDESPREAD OR DENSE THIS FOG WILL BECOME WITH NEAR TERM MODELS
OFTEN OVER-FORECASTING THE EXTENT AND DEGREE OF SEA FOG THIS
TIME OF YEAR. SHOULD ANY FOG DEVELOP, SOME OF THIS MAY BRUSH THE
LOWER SOUTH CAROLINA COAST, ESPECIALLY FROM TYBEE ISLAND
NORTHWARD. PATCHY FOG WAS INTRODUCED FOR THE IMMEDIATE COASTAL
AREAS AND AS FAR INLAND AS (ROUGHLY) THE US-17 CORRIDOR IN
CHARLESTON COUNTY. ADJUSTMENTS TO THE FOG FORECAST MAY VERY WELL
BE NEEDED LATER TODAY AS SHORTER TERM TRENDS BECOME MORE
APPARENT.
SHORT TERM /MONDAY THROUGH WEDNESDAY/
FOR MONDAY MORNING, WE'LL BE WATCHING A COLD FRONT MOVE TOWARDS
THE AREA FROM THE WEST, WITH A STRONG MID-LEVEL TROUGH
SIMILARLY MOVING TOWARDS THE AREA. EXPECT BREEZY WINDS TO
QUICKLY DEVELOP AS THE TEMPERATURE INVERSION MIXES OUT, ALLOWING
FOR THE STRONG WINDS FROM THE LOW-LEVEL JET TO BE BROUGHT TO
THE SURFACE. SUSTAINED WINDS OUT OF THE SOUTHWEST IN THE TEENS
TO LOWER 20S WITH GUSTS IN THE UPPER 20S TO LOWER 30S ARE
EXPECTED OUT AHEAD OF THE FRONT. TEMPERATURES WILL REMAIN
SEASONABLY WARM IN THE UPPER 60S TO LOWER 70S, COLDEST FOR
INLAND AREAS DUE TO THE COLD FRONT MOVING FROM WEST TO EAST,
WITH TEMPERATURES DROPPING THROUGHOUT THE AFTERNOON HOURS.
BEHIND THE FRONTAL PASSAGE, WINDS SWING AROUND TO BECOME OUT OF
THE NORTHWEST, REMAINING SIMILARLY BREEZY AMIDST COLD-AIR
ADVECTION AND INCREASING PRESSURE ADVECTION.
LAKE WINDS: GIVEN PERIODS OF SUSTAINED WINDS ABOVE 20 KNOTS AND
GUSTS OVER 25 KNOTS, A LAKE WIND ADVISORY FOR LAKE MOULTRIE
WILL LIKELY BE NEEDED STARTING MONDAY AFTERNOON AND CONTINUING
INTO THE EARLY OVERNIGHT PERIOD ON TUESDAY.
IN ADDITION TO THE BREEZY WINDS, MODELS CONTINUE TO SHOW A BAND
OF BROKEN LIGHT RAIN SHOWERS DEVELOPING ALONG/AHEAD OF THE
FRONT MONDAY MORNING INTO THE AFTERNOON HOURS. HOWEVER, GIVEN
PWATS NEAR AN INCH AND RATHER MEAGER INSTABILITY, ANY RAINFALL
AMOUNTS ARE EXPECTED TO BE LIGHT AT UNDER A TENTH OF AN INCH.
MUCH COOLER AIR IS BROUGHT IN BEHIND THE COLD FRONT, WITH
TUESDAY MORNING TEMPERATURES EXPECTED IN THE LOWER TO UPPER 30S,
WARMEST ALONG THE COAST. WIND CHILLS INTO THE MID TO UPPER 20S
ARE EXPECTED, SO BE SURE TO DRESS APPROPRIATELY TUESDAY MORNING
AS THIS WILL FEEL MUCH COOLER THAN IT HAS BEEN AS OF LATE. WHILE
NOT QUITE AS BREEZY, NORTHWEST WINDS GUSTING INTO THE MID TO
UPPER TEENS WILL BE CONTINUING THROUGHOUT THE DAY ON TUESDAY,
WITH AFTERNOON HIGHS ONLY EXPECTED TO REACH THE LOWER 50S GIVEN
THE CONTINUED COLD-AIR ADVECTION.
AS THE COLD-AIR ADVECTION DWINDLES INTO THE OVERNIGHT PERIOD,
WINDS WILL WEAKEN ALLOWING FOR RADIATIONAL COOLING TO TAKE
AFFECT FOR THE REST OF THE OVERNIGHT HOURS. WILL LIKELY SEE
EARLY MORNING TEMPERATURES DIP DOWN INTO THE MID 20S INLAND,
THOUGH WINDS CURRENTLY LOOK WEAK ENOUGH TO NOT SEE WIND CHILLS
BELOW COLD WEATHER ADVISORY CRITERIA OF 20 DEGREES OR LESS.
CLOSER TO THE COAST, EXPECT LOW TEMPERATURES WEDNESDAY MORNING
IN THE LOWER/MID 30S. TEMPERATURES BEGIN TO MODERATE ON
WEDNESDAY, WITH AMPLE SUNSHINE BRINGING THE REGION BACK UP INTO
THE MID 50S.
LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/
UPPER LEVEL TROUGH AXIS MOVES ACROSS THE AREA OVERNIGHT INTO
THURSDAY, WITH A SURFACE HIGH PRESSURE MOVING INTO THE EASTERN
GULF. THIS WILL LIKELY KEEP WINDS JUST STRONG ENOUGH TO LIMIT
RADIATIONAL COOLING, THOUGH OVERNIGHT TEMPERATURES INTO THURSDAY
MAY DIP CLOSE TO FREEZING FOR INLAND AREAS, CLOSER TO THE UPPER
30S FOR AREAS ALONG THE COAST. TEMPERATURES CONTINUE TO
MODERATE THURSDAY AND FRIDAY, RISING INTO THE UPPER 50S AND
LOWER TO MID 60S RESPECTIVELY.
A WEAK SHORTWAVE LOOKS TO MOVE TOWARDS/ACROSS THE AREA ON
SATURDAY, ACCOMPANIED BY A SURFACE LOW PRESSURE SYSTEM IN SOME
MODELS, BRINGING A CHANCE FOR LIGHT RAIN SHOWERS.
AVIATION /12Z SUNDAY THROUGH THURSDAY/
28/12Z TAF DISCUSSION:
KCHS/KJZI: THE BACKDOOR FRONT HAS PUSHED SOUTH OF BOTH
TERMINALS. THE RISK FOR FOG AT KJZI THROUGH DAYBREAK HAS ENDED.
VFR WILL PREVAIL AT BOTH TERMINALS THROUGH 29/12Z. ISOLATED
SHOWERS COULD DEVELOP NEAR THE TERMINALS LATER THIS MORNING
THROUGH EARLY AFTERNOON AS THE FRONT LIFTS BACK TO THE NORTH,
BUT NO MEANINGFUL IMPACTS ARE EXPECTED. VCSH WAS INTRODUCED
18-00Z. THERE IS A CHANCE THAT SOME DEGREE OF SEA FOG OR VERY
LOW STRATUS COULD IMPACT KJZI LATER THIS EVENING AS CONDITIONS
FAVOR ITS DEVELOPMENT OFFSHORE. THE LOW- LEVEL FLOW WILL BECOME
FAVORABLE FOR ANY SEA FOG THAT FORMS TO BRUSH THE COAST.
CONFIDENCE ON IMPACTS THIS FAR OUT IS VERY LOW, SO NO MENTION OF
FOG OR LOW STATUS WAS INCLUDED FOR THE 12Z TAF CYCLE.
KSAV: KSAV WEBCAM SHOWS VSBYS HAVE BEEN JUMPING AROUND OVER THE
PAST FEW HOURS. THE RISK FOR SOME REDUCED VSBYS WILL PERSIST
THROUGH ABOUT 14Z THEN VFR WILL PREVAIL THROUGH 29/12Z.
EXTENDED AVIATION OUTLOOK: GUSTY WINDS ARE POSSIBLE ON MONDAY,
ALONG WITH A BRIEF PERIOD WHERE MVFR CIGS ARE EXPECTED AS WEAK
RAIN SHOWERS MOVE IN ALONG A COLD FRONT. CONDITIONS IMPROVE
SHORTLY THEREAFTER, WITH VFR CONDITIONS EXPECTED INTO THE
EXTENDED PERIOD.
MARINE
THROUGH TONIGHT: A WEAK BACKDOOR FRONT WILL BRIEFLY STALL NEAR
THE SAVANNAH RIVER ENTRANCE LATER THIS MORNING, THEN SLOWLY
DRIFT BACK TO THE NORTH LATER IN THE DAY. WINDS WILL BE EAST TO
NORTHEAST AS HIGH AS 10 KT NORTH OF THE FRONT AND VARIABLE TO
SOUTHERLY LESS THAN 10 KT SOUTH OF THE FRONT. THE FRONT SHOULD
CLEAR THE SOUTH SANTEE-EDISTO BEACH NEARSHORE WATERS BY LATE
THIS AFTERNOON WITH SOUTH TO SOUTHWEST WINDS PREVAILING TONIGHT
AHEAD OF A COLD FRONT. WINDS TONIGHT WILL INCREASE TO 10-15 KT.
SEA FOG: THERE IS CONCERN FOR THE DEVELOPMENT OF SEA FOG LATER
TODAY AND ESPECIALLY TONIGHT AS WARM AIR PARCELS ADVECT OVER THE
COOLER NEARSHORE WATERS WHERE SEA SURFACE TEMPERATURES ARE
CURRENTLY IN THE MID-UPPER 50S. HREF GRAND ENSEMBLE
PROBABILITIES FOR VSBYS <1NM INCREASE TO 50-70% ACROSS THE
GEORGIA AND FAR SOUTHERN WATERS BY THIS AFTERNOON AND EXPAND TO
60-80% ACROSS ALL WATERS THIS EVENING. MODELS DO HAVE A HISTORY
OF BEING TOO AGGRESSIVE WITH THE DEGREE AND EXPANSE OF SEA FOG,
ESPECIALLY GIVEN THE MARGINAL SEA SURFACE TEMPERATURES ARE IN
PLACE, SO THESE PROBABILITIES SHOULD BE USED WITH CAUTION.
THERE IS TOO JUST MUCH UNCERTAINTY TO INTRODUCE ANYTHING MORE
THAN PATCHY DENSE FOG AT THIS TIME, ESPECIALLY GIVEN MODEL
AGGRESSIVE TENDENCIES AND MARGINAL SEA SURFACE TEMPERATURES.
MARINE DENSE FOG ADVISORIES MAY BECOME NECESSARY IF THE SEA FOG
DOES DEVELOP AS MUCH OF THE GUIDANCE SUGGESTS AND VSBYS 1 NM OR
LESS ARE REALIZED.
MONDAY THROUGH TUESDAY: AHEAD OF A STRONG COLD FRONT, MONDAY
WILL SEE SOUTHWESTERLY WINDS INCREASING TO 20 KNOTS AND GUSTS TO
30 KTS WITH SEAS BUILDING. A COLD FRONT WILL BRING A SHIFT IN
WINDS LATE MONDAY AFTERNOON INTO THE EVENING, CONTINUING THE
BREEZY WINDS OUT OF THE NORTHWEST. SEAS NEAR 6 FEET ARE EXPECTED
WELL OFFSHORE IN THE WATERS FROM SOUTH SANTEE RIVER TO EDISTO
BEACH SC, AND ALSO THE WATERS FROM SAVANNAH GA TO ALTAMAHA SOUND
GA ROUGHLY 40 TO 60 NM OUT. SMALL CRAFT ADVISORIES MAY HAVE
BEEN POSTED FOR ALL WATERS, NOT INCLUDING THE CHARLESTON HARBOR
AS WINDS LOOK TO REMAIN BELOW ADVISORY THRESHOLDS.
WEDNESDAY AND THURSDAY: SURFACE HIGH PRESSURE BUILDS ACROSS THE
SOUTHEAST ON WEDNESDAY, BRINGING IMPROVING CONDITIONS WEDNESDAY
INTO FRIDAY.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY FROM 7 AM MONDAY TO 7 AM EST TUESDAY FOR
AMZ350.
SMALL CRAFT ADVISORY FROM 1 PM MONDAY TO 4 AM EST TUESDAY FOR
AMZ352.
SMALL CRAFT ADVISORY FROM 4 PM MONDAY TO 4 AM EST TUESDAY FOR
AMZ354.
SMALL CRAFT ADVISORY FROM 10 AM MONDAY TO 1 PM EST TUESDAY FOR
AMZ374.
NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...
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