537
FXUS62 KCHS 241811
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
111 PM EST SAT JAN 24 2026
WHAT HAS CHANGED
UPDATED THE EQUIPMENT SECTION, KCLX WILL REMAIN DOWN UNTIL
MONDAY. THE POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS WAS
INCLUDED IN KEY MESSAGE 1. THE AVIATION SECTION HAS BEEN UPDATED
TO REFLECT THE 18Z TAFS.
KEY MESSAGES
- 1) WIDESPREAD PRECIPITATION IS EXPECTED TONIGHT THROUGH SUNDAY
NIGHT, WITH FREEZING RAIN POSSIBLE TONIGHT INTO SUNDAY MORNING
ACROSS INLAND PORTIONS OF THE SC LOWCOUNTRY AND SE GA.
- 2) ARCTIC AIR WILL YIELD VERY COLD TEMPERATURES MONDAY NIGHT
INTO NEXT WEEKEND, WITH COLD WEATHER ADVISORIES POSSIBLE.
DISCUSSION
KEY MESSAGE 1: WIDESPREAD PRECIPITATION IS EXPECTED TONIGHT THROUGH SUNDAY
NIGHT, WITH FREEZING RAIN POSSIBLE TONIGHT INTO SUNDAY MORNING
ACROSS INLAND PORTIONS OF THE SC LOWCOUNTRY AND SE GA.
INFRARED SATELLITE TODAY IS VERY INTERESTING, SHOWING THE ARCTIC
SURGING SOUTHWARD FROM CENTRAL CANADA OVER THE U.S., SPANNING THE
AREA FROM THE GREAT PLAINS TO NEW ENGLAND. BY THIS AFTERNOON, THE
CENTER OF THE 1040 MB HIGH WILL SLIDE OVER NEW ENGLAND, RIDGING
SOUTH ALONG THE EAST FACING SLOPES OF THE APPALACHIANS. COLD AIR
DAMMING (CAD) WILL CONTINUE TO BUILD THROUGH TONIGHT, RAPIDLY
COOLING TEMPERATURES AND DEEPENING THE CAD ACROSS THE FORECAST AREA
THIS EVENING. NEAR-TERM GUIDANCE INDICATES THAT A SFC LOW WILL
ORGANIZE AND DEVELOP OVER THE GULF STREAM THIS EVENING AS H5
LONGWAVE TROUGH APPROACHES FROM THE WEST. ONCE THE LOW DEVELOPS, IT
IS EXPECTED TO TRACK NORTHEAST OFF THE SC COAST TONIGHT.
AS THE LOW PASSES OFF THE COAST, ISENTROPIC LIFT WILL INCREASE
ACROSS THE FORECAST AREA, ESPECIALLY ALONG AND WEST OF THE I-95
CORRIDOR. NAM12 SHOWS ISENTROPIC LIFT INCREASING BETWEEN 285-295K
THIS AFTERNOON, GENERALLY REMAINING INTO THE DAYLIGHT HOURS SUNDAY
MORNING. FORECAST SOUNDINGS INDICATED SATURATED CONDITIONS BELOW H7,
ESPECIALLY BELOW A STRONG WARM NOSE CENTERED AT H9. THE COMBINATION
OF THE PW IN EXCESS OF AN INCH WITH ROUNDS OF ISENTROPIC LIFT SHOULD
YIELD ROUNDS OF DRIZZLE OR LIGHT PRECIP WITHIN THE WEDGED AIR MASS.
THE FALLING PRECIP SHOULD LEAD TO SOME DEGREE OF DIABATIC COOLING AS
TEMPERATURE APPROACH THE WET BULB. IN ADDITION, STEADY NNE WINDS WILL
ADVECT COOLER TEMPERATURES ACROSS THE SC LOWCOUNTRY AND SE GA
TONIGHT. HIGH RESOLUTION GUIDANCE INDICATES THAT THE FREEZING LINE
WILL PUSH OVER THE INTERIOR COUNTIES, JENKINS COUNTY NORTH TO
BERKELEY COUNTY, BY DAYBREAK SUNDAY. THIS CORRIDOR OF COUNTIES IS
EXPECTED TO SEE AN OVERLAP OF LIGHT PRECIP WITH SUB-FREEZING
TEMPERATURES, RESULTING IN ROUNDS OF FREEZING RAIN OR FREEZING
DRIZZLE. GUIDANCE AS TRENDED A BIT DRIER, BUT AT LEAST A LIGHT GLAZE
TO A FEW HUNDREDTHS OF AN INCH OF ICE IS POSSIBLE BY EARLY SUNDAY
MORNING. A WINTER WEATHER ADVISORY WILL REMAIN FOR A TIER OF
COUNTIES FROM JENKINS COUNTY EAST TO BERKELEY COUNTY FROM 7 PM THIS
EVENING UNTIL 1 PM SUNDAY.
GUIDANCE CONTINUES TO INDICATE A STRONG COLD FRONT APPROACHING THE
CWA FROM THE WEST ON SUNDAY, TIMED TO REACH THE INLAND COUNTIES
DURING THE EARLY EVENING AND THE COAST BY MIDNIGHT. HIGH RESOLUTION
GUIDANCE SHOWS A SOLID BAND OF SHOWERS WITH EMBEDDED THUNDERSTORMS
REMAIN ALONG AND AHEAD OF THE COLD FRONT. FORECAST SOUNDINGS
INDICATE THAT WEAK INSTABILITY MAY DEVELOP AHEAD OF THE LINE,
RESULTING IN 100-200 J/KG OF CAPE ACROSS PORTIONS OF SE GA. HOWEVER,
WIND SHEAR REMAINS VERY STRONG, FEATURING 0-1 KM SRH IN EXCESS 250
M2/S2 AND BULK SHEAR AROUND 50 KTS. 12Z HREF INDICATES STP VALUES
APPROACHING ONE UNIT ACROSS EXTREME SE GA. IT IS POSSIBLE THAT A
SEVERE THUNDERSTORM OR TWO COULD REACH SE GA SUNDAY EVENING, SOME
POSSIBLY FEATURE QLCS STRUCTURE WITH ROTATING UPDRAFTS. ELSEWHERE,
STRONG THUNDERSTORMS REMAIN POSSIBLE, WITH WIND GUSTS AS THE PRIMARY
THREAT. COLD AIR WILL FOLLOW THE COLD FRONT, HOWEVER ALL MOISTURE IS
EXPECTED TO BE OFFSHORE BY THE TIME THE COLD AIR ARRIVES.
KEY MESSAGE 2: ARCTIC AIR WILL YIELD VERY COLD TEMPERATURES MONDAY NIGHT
INTO NEXT WEEKEND, WITH COLD WEATHER ADVISORIES POSSIBLE.
AS A STRONG ARCTIC HIGH PRESSURE USHERS COLD, DRY AIR INTO THE
REGION BEHIND A COLD FRONT ON MONDAY NIGHT/TUESDAY MORNING, TEMPS.
ARE FORECAST TO DROP INTO THE TEENS AND LOW 20S WEST OF I-95 AND
ACROSS MUCH OF THE FRANCIS MARION FORECAST. IT'LL BE A TAD WARMER
NEAR THE COASTLINE WITH TEMPS. RANGING IN THE LOW TO MID 20S. MIXED
THE NAM12/NBM10 INTO THE OVERNIGHT TEMPERATURES AS THE NBM APPEARED
TO BE STRUGGLING TO REALIZE THE PRESENCE OF THE COLD-AIR DAMMING
(CAD) ACROSS THE REGION. THESE CONDITIONS COMBINED WITH LIGHT WEST-
NORTHWESTERLY WINDS COULD RESULT IN WIDESPREAD WIND CHILL VALUES IN
THE MID TO UPPER TEENS FROM INTERIOR COUNTIES ALL THE WAY DOWN TO
THE COASTLINE. SOME GUIDANCE HAS BEEN INDICATING THAT MINIMUM WIND
CHILL VALUES COULD DROP RANGE AROUND 10 DEGREES ACROSS PORTIONS OF
INLAND SE GA. A COLD WEATHER ADVISORY SHOULD EVENTUALLY BE NEEDED
FOR THE ENTIRE AREA ACROSS SOUTHEAST SOUTH CAROLINA AND SOUTHEAST
GEORGIA. FORECAST REMAINS A BIT WARMER ON TUESDAY NIGHT/WEDNESDAY
MORNING AS TEMPS. RANGE IN THE LOW TO MID 20S ACROSS THE INTERIOR
COUNTIES WITH LOW 30S ALONG THE COASTLINE. THUS, CONFIDENCE WITH
NEEDING A COLD WEATHER ADVISORY SEEM LESS LIKELY FOR THIS TIME
PERIOD WITH PROBABILITIES FOR TEMPS. LESS THAN 20 DEGREES RANGE FROM
20-40%. IT'S IMPORTANT TO NOTE THAT MODEL CONFIDENCE CONTINUES TO BE
FAIRLY HIGH AS THE IQR SHOWS A 1 TO 2 DEGREE SPREAD FOR LOWS TUESDAY
AND WEDNESDAY MORNING.
THIS COLD AIRMASS WILL LIKELY STICK AROUND THROUGH LATE THIS WEEK AS
A REINFORCING COLD FRONT MOVES THROUGH ON THURSDAY AND PUSHES
ANOTHER SHOT OF COLD AIR INTO THE REGION FROM THE NORTHWEST. IT'S
REASONABLE TO SAY THAT WE COULD HAVE A FEW HOURS OF WIND CHILL
VALUES BELOW 20 EVERY MORNING INTO THE WEEKEND AND ADDITIONAL COLD
WEATHER ADVISORIES MIGHT BE NEEDED.
AVIATION /18Z SATURDAY THROUGH THURSDAY/
18Z TAFS: GUSTY NORTHEAST WINDS WITH MVFR CEILINGS WILL REMAIN
ACROSS THE TERMINALS THIS AFTERNOON. GUSTS MAY DECREASE THIS
EVENING, HOWEVER, CLOUD BASES SHOULD LOWER THROUGH THE REST OF THE
NIGHT DUE TO STRENGTHENING LLVL LIFT. IFR CEILINGS WITH PERIODS OF
LIGHT DRIZZLE POSSIBLE BY 5Z. IFR CEILINGS WITH NORTHEAST WINDS WILL
CONTINUE ACROSS THE TERMINALS THROUGH MID-DAY SUNDAY. WINDS COULD
TURN FROM THE SE AT KSAV LATE IN THE TAF PERIOD AS A STRONG COLD
FRONT APPROACHES FROM THE WEST.
EXTENDED AVIATION FORECAST: EXPECT A COLD FRONT TO MOVE ACROSS THE
REGION SUNDAY NIGHT AND YIELD VFR CONDITIONS THROUGH EARLY NEXT WEEK.
MARINE
THROUGH TONIGHT: AS AN ARCTIC HIGH PRESSURE EXPANDS ACROSS THE
SOUTHEAST, STRONG COLD AIR ADVECTION (CAA) WILL CONTINUE TO PUSH
ACROSS THE LOCAL WATERS ALLOWING MARINE CONDITIONS TO FURTHER
DETERIORATE. A WEAK LOW PRESSURE SYSTEM WILL ALSO ATTEMPT TO DEVELOP
NEAR THE COLD FRONT LOCATED OFFSHORE, YIELDING THE CONTINUATION OF
AN ENHANCED PRESSURE GRADIENT. EXPECT FAIRLY STRONG NORTHEASTERLY
WINDS AT 20 TO 25 KT WITH GUSTS UP TO 30 KT. CHARLESTON PILOT BOATS
REPORTED CHAOTIC SEAS THIS MORNING (~10AM) AS THE EAST-SOUTHEASTERLY
SWELL CHURNS WAVE HEIGHTS UP TO 7 TO 10 FT. SOME GUIDANCE HAS BEEN
HINTING AT GALE-FORCE GUSTS ACROSS THE NEARSHORE CHARLESTON WATERS
THIS AFTERNOON, AND THIS WILL CONTINUE TO BE MONITORED. SMALL CRAFT
ADVISORIES HAVE BEEN ISSUED FOR ALL MARINE ZONES (INCLUDING THE
CHARLESTON HARBOR). LIGHT RAIN SHOWERS WILL START THIS EVENING
ACROSS THE WATERS AND CONTINUE THROUGH THE OVERNIGHT AS THIS
AFOREMENTIONED LOW PRESSURE SHIFTS NORTHEASTWARD OVER THE ATLANTIC.
SUNDAY THROUGH WEDNESDAY: AS A STRONG COLD FRONT APPROACHES THE
REGION FROM A LOW PRESSURE SYSTEM MOVING ACROSS THE SOUTHEAST,
HAZARDOUS MARINE CONDITIONS CONTINUE TO PERSIST THROUGH EARLY NEXT
WEEK. NORTHEASTERLY FLOW WILL VEER OUT OF THE SOUTH SUNDAY AFTERNOON
WITH WIND SPEEDS OF 20 TO 25 KT WITH GUSTS UP TO 30 KT POSSIBLE.
SEAS REMAIN A BIT CHAOTIC WITH WAVE HEIGHTS 6+ FT ON SUNDAY AND
MONDAY, AND THEN EXPECT THE SWELL TO RETREAT ON MONDAY NIGHT AND
SEAS TO SLOWLY DIMINISH. SMALL CRAFT ADVISORIES REMAIN IN EFFECT
UNTIL TUESDAY MORNING GIVEN THE ELEVATED WINDS AND SEAS.
EQUIPMENT
THE KCLX RADAR WILL REMAIN OUT OF SERVICE. CRITICAL PARTS ARE ON
ORDER AND SHOULD ARRIVE ON MONDAY. USERS SHOULD USE ADJACENT WSR-88D
SITES, INCLUDING KCAE, KLTX, KJAX, KVAX AND KJGX.
CHS WATCHES/WARNINGS/ADVISORIES
GA...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 1 PM EST
SUNDAY FOR GAZ087-088.
SC...WINTER WEATHER ADVISORY FROM 7 PM THIS EVENING TO 1 PM EST
SUNDAY FOR SCZ040-042>045.
MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR AMZ330.
SMALL CRAFT ADVISORY UNTIL 10 AM EST TUESDAY FOR AMZ350-352-
354-374.
DENNIS/NED
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