010
FXUS62 KCHS 181651
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
1151 AM EST SAT JAN 18 2025
SYNOPSIS
AN AREA OF LOW PRESSURE AND ASSOCIATED COLD FRONT WILL IMPACT
THE REGION TODAY THROUGH SUNDAY MORNING. ANOTHER LOW PRESSURE
SYSTEM COULD IMPACT THE REGION EARLY TO MID NEXT WEEK.
NEAR TERM /THROUGH TONIGHT/
THIS AFTERNOON: TEMPERATURES HAVE HAD A HARD TIME RISING TODAY
WITH WIDESPREAD RAINS IMPACTING THE AREA. SOME TEMPERATURE
RECOVER COULD OCCUR LATER THIS AFTERNOON, BUT CURRENT NEAR TERM
MODEL AND OBSERVATIONAL TRENDS SUGGEST HIGHS NEED TO BE NUDGED
DOWN ONCE AGAIN, ESPECIALLY FAR INTERIOR UP INTO THE CHARLESTON
METRO AREA.
TONIGHT: LATEST GUIDANCE SUGGESTS A SECOND ROUND OF PRECIP
OCCURRING DURING THE OVERNIGHT PERIOD, PRIMARILY LATE EVENING
AND INTO LATE NIGHT AS LOW PRESSURE DEVELOPS ALONG THE SOUTHERN
FLANK OF A COLD FRONT APPROACHING THE LOCAL AREA WITHIN A FEW
HOURS PRIOR TO DAYBREAK. FOR THIS REASON, THE LATEST FORECAST
REFLECTS PRECIP CHANCES INCREASING ONCE AGAIN LATE EVENING, THEN
SLOWLY SHIFTING EAST-SOUTHEAST WITH TIME AS THE FRONT NEARS.
TEMPS WILL REMAIN MILD THROUGH THE NIGHT AHEAD OF THE FRONT,
GENERALLY RANGING IN THE LOW- MID 50S FOR MOST AREAS. A FEW
LOCATIONS COULD DIP INTO THE UPPER 40S POST FROPA, PRIMARILY
WELL INLAND AND/OR NORTH LATE.
SHORT TERM /SUNDAY THROUGH TUESDAY/
SUNDAY AND SUNDAY NIGHT: AHEAD OF THE APPROACHING COLD FRONT,
TEMPERATURES WILL BE ABLE TO REACH INTO THE LOW TO MID 60S
MAKING IT PROBABLY THE WARMEST DAY THIS WEEK. ANY PRECIPITATION
SHOULD CLEAR OUT IN THE MORNING AND ALLOW FOR A RAIN-FREE
AFTERNOON. THE COLD FRONT WILL PASS THROUGH THE REGION BY THE
AFTERNOON AND TEMPERATURES WILL BEGIN TO DROP THROUGHOUT THE
AFTERNOON AS COLD, DRY AIR ADVECTS INTO THE REGION BEHIND THE
FRONT. ALONG WITH THIS, NORTHWESTERLY WINDS COULD BECOME QUITE
BREEZY BEHIND THE FRONT WITH WIND SPEEDS CLIMBING TO 10 TO 15
MPH WITH GUSTS OF 20 MPH. OVERNIGHT, LOWS WILL DROP INTO THE LOW
20S INLAND AND MID TO UPPER 20S CLOSER TO COASTLINE. HOWEVER,
WINDS WILL MAKE TEMPERATURES FEEL CLOSER TO THE 15-20 DEGREE
RANGE, WHICH IS SOLIDLY IN THE COLD WEATHER ADVISORY CRITERIA.
MONDAY AND MONDAY NIGHT: ALONG WITH POST-FRONTAL COLD AIR
ADVECTION, A STRONG ARCTIC AIR MASS WILL BEGIN TO SETTLE INTO
THE REGION AND THE FORECAST LOOKS TO REMAIN COLD AND DRY. HIGHS
WILL ONLY REACH INTO THE LOWER 40S. LOWS WILL DROP INTO THE LOW
20S INLAND AND MID TO UPPER 20S CLOSER TO THE COASTLINE. THESE
TEMPS WILL SUPPORT ANOTHER NIGHT OF WIND CHILL TEMPS IN THE
15-20 DEGREE RANGE, WHICH IS AGAIN SOLIDLY IN THE COLD WEATHER
ADVISORY CRITERIA.
TUESDAY: LATEST OPERATIONAL RUNS OF THE GFS, ECMWF, AND CMC ARE
IN AGREEMENT THAT A LOW PRESSURE SYSTEM FROM THE GULF OF MEXICO
WILL BEGIN TO TRACK EAST ACROSS FLORIDA TOWARDS THE REGION AND
POTENTIALLY BRING IMPACTS, POSSIBLY SIGNIFICANT, TO SOUTHEAST
SOUTH CAROLINA AND SOUTHEAST GEORGIA. THERE STILL REMAINS SOME
UNCERTAINTY ON THE P-TYPES, BUT SEEMS FAVORABLE FOR A
SNOW/FREEZING RAIN EVENT TO UNFOLD. AS FAR AS TIMING GOES, THE
BEST CHANCE FOR FROZEN PRECIPITATION TO BEGIN LOOKS TO BE
TUESDAY AFTERNOON AND POPS WERE INCREASED ACCORDINGLY. WITH
STRONG, COLD AIR IN PLACE, HIGHS WILL ONLY REACH INTO THE MID
30S INLAND AND UPPER 30S/LOW 40S CLOSER TO THE COASTLINE.
LAKE WINDS: BREEZY CONDITIONS WILL DEVELOP ON LAKE MOULTRIE
LATE SUNDAY AFTERNOON AS A COLD FRONT PUSHES THROUGH. STRONG
POST-FRONTAL COLD AIR ADVECTION WILL PUSH WINDS INTO THE 15-20
KT RANGE WITH GUSTS 25-30 KT SUNDAY NIGHT AND A LAKE WIND
ADVISORY COULD BE NEEDED DURING THIS TIME. SPEEDS SHOULD BELOW
ADVISORY CRITERIA BY MID- MORNING MONDAY.
LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/
TRANSITIONING INTO TUESDAY NIGHT AND BEYOND, THE LOW PRESSURE
SYSTEM SEEMS TO TRACK TO THE FORECAST IS PRETTY MUCH ON TRACK,
BUT POPS WERE BUMPED BACK UP TO 100% GIVEN CURRENT RADAR AND
HREF TRENDS. HOURLY TEMPERATURES WILL BE A BIT UNUSUAL TODAY AS
DIURNAL HEATING WILL BE FIGHTING SOME DIABATIC COOLING WITH THE
APPROACHING RAIN SHIELD. HIGHS WERE NUDGED A TAD LOWER IN SOME
SPOTS, BUT THE GENERAL FLAVOR FOR HIGHS IN THE UPPER 50S/LOWER
60S.HE SOUTH AND OFFSHORE TUESDAY NIGHT AND BRING WINTRY MIX TO
THE REGION. IT IS STILL TOO FAR OUT TO IDENTITY ANY SPECIFIC
SNOW AND ICE ACCUMULATIONS. AS FAR AS TIMING GOES FOR THIS
EVENT, THE GREATEST IMPACTS APPEAR TO BE TUESDAY NIGHT THROUGH
WEDNESDAY MORNING WHEN THE COLDEST AIR WILL ALIGN WITH THE
STRONGEST FORCING AND HEAVIEST PRECIPITATION. MOST OF THE MODELS
ARE IN AGREEMENT THAT MOST OF THE PRECIPITATION SHOULD END BY
WEDNESDAY AFTERNOON.
IN ADDITION TO THIS SYSTEM, IT WILL BE DOWN RIGHT COLD. IF ANY
SNOW AND ICE ACCUMULATE, IT WILL BE STICKING AROUND FOR A COUPLE
DAYS. HIGHS WILL ONLY REACH INTO THE 30S BOTH TUESDAY AND
WEDNESDAY. LOWS ON TUESDAY NIGHT WILL DROP INTO THE LOW TO MID
20S WITH WIND CHILL VALUES IN THE MID-TEENS. THUS, A COLD
WEATHER ADVISORY WILL LIKELY BE NEEDED TUESDAY NIGHT. LOWS ON
WEDNESDAY NIGHT GET EVEN COLDER WITH TEMPERATURES DROPPING INTO
THE THE MID-TEENS AND WIND CHILL VALUES DIPPING BELOW 10 DEGREES
IN SOME LOCATIONS. THIS IS REACHING EXTREME COLD WARNING
TERRITORY (10 DEGREES OR COLDER) AND WILL LIKELY NEED TO BE
ISSUED WEDNESDAY NIGHT. WE COULD EVEN BREAK THE RECORD LOW
TEMPERATURES AT KCHS/KCXM/KSAV ON THURSDAY.
ANOTHER AREA OF LOW PRESSURE COULD DEVELOP OFF THE SOUTH
CAROLINA COAST THURSDAY AND APPEARS TO LINGER AROUND FOR A BIT.
WITH TEMPERATURES STILL QUITE COLD, A CHANCE OF FREEZING RAIN
WAS MENTIONED ON THURSDAY, FRIDAY, AND SATURDAY MORNING. DUE TO
THIS BEING FAR OUT IN THE FORECAST, POPS WERE KEPT AT A LOW
CHANCE.
AVIATION /15Z SATURDAY THROUGH WEDNESDAY/
18/18Z TAF DISCUSSION:
KCHS/KJZI/KSAV: IFR CIGS WILL SPREAD OVER ALL TERMINALS TODAY
AND PERSIST INTO TONIGHT AS WAVES OF MOSTLY LIGHT RAIN MOVE
THROUGH. VSBYS SHOULD GENERALLY GO NO LOWER THAN MVFR, BUT MAY
BRIEFLY DROP TO IFR AT TIMES, ESPECIALLY THIS EVENING AT KSAV AS
A BAND OF HEAVIER RAINFALL PUSHES OFFSHORE. A RETURN TO MVFR
CIGS SHOULD OCCUR BY MID-MORNING SUNDAY.
EXTENDED AVIATION OUTLOOK: FLIGHT RESTRICTIONS ARE LIKELY
SATURDAY NIGHT INTO SUNDAY MORNING AS WIDESPREAD RAINS MOVE
THROUGH IN ASSOCIATION WITH A COLD FRONT. THE RISK FOR
RESTRICTIONS IN LOW VSBYS AND CEILINGS WILL RETURN TUESDAY
MORNING INTO WEDNESDAY MORNING AS A POTENTIAL WINTER STORM
IMPACTS THE REGION. THERE IS AN INCREASING CHANCE FOR FREEZING
OR FROZEN PRECIPITATION TO IMPACT ALL TERMINALS DURING THIS TIME
PERIOD.
MARINE
TODAY AND TONIGHT: A WEAK PRESSURE GRADIENT WILL BE IN PLACE
FOR MUCH OF THE DAY WHILE A COASTAL TROUGH/LOW SHIFTS NORTH AND
AWAY FROM THE LOCAL AREA THIS MORNING INTO EARLY AFTERNOON. IN
GENERAL, SOUTHEAST WINDS UPWARDS TO 5-10 KT WILL TURN MORE
SOUTH-SOUTHWEST THIS AFTERNOON. SEAS WILL RANGE BETWEEN 1-2 FT.
THE PRESSURE GRADIENT SHOULD SLOWLY STRENGTHEN THIS EVENING AND
OVERNIGHT AS LOW PRESSURE AND ITS ASSOCIATED FRONT NEARS. FOR
THIS REASON, SOUTH- SOUTHWEST WINDS WILL LIKELY INCREASE TO THE
10-15 KT THIS EVENING, WITH EVEN SOME GUSTS AROUND 20 KT AFTER
MIDNIGHT. SEAS WILL ALSO BUILD TO 3-5 FT TONIGHT, LARGEST ACROSS
NORTHERN SOUTH CAROLINA WATERS OFF THE CHARLESTON COUNTY COAST.
SUNDAY: A COLD FRONT WILL BE LOCATED OVER OR NEAR THE COASTAL
WATERS EARLY IN THE MORNING. IT'LL QUICKLY MOVE OFFSHORE AS THE
DAY PROGRESSES. STRONG, BROAD HIGH PRESSURE WILL THEN GRADUALLY
BUILD IN FROM THE PLAINS STATES. THE COMBINATION OF AN ENHANCED
PRESSURE GRADIENT AND STRONG COLD AIR ADVECTION WILL CAUSE SW
WINDS DURING THE DAY TO TURN TO THE NW DURING THE EVENING AND
INCREASE. WIND GUSTS WILL PROBABLY REACH 25 KT FOR ALL OF THE
WATERS, INCLUDING THE CHARLESTON HARBOR. SMALL CRAFT ADVISORIES
WILL BE NEEDED STARTING IN THE AFTERNOON AND GOING FOR MOST OF
THE NIGHT. CONDITIONS START TO IMPROVE BEFORE DAYBREAK SATURDAY.
MONDAY: STRONG HIGH PRESSURE WILL BE LOCATED OVER THE MIDDLE MS
VALLEY IN THE MORNING. IT'LL SHIFT EASTWARD, BECOMING CENTERED
OVER THE MID-ATLANTIC REGION OVERNIGHT. FOR THE SECOND HALF OF
THE NIGHT, TROUGHING DEVELOPS JUST SOUTH OF OUR COAST AND USHERS
MOISTURE TO THE NORTH. THIS SYNOPTIC PATTERN WILL CAUSE GUSTY
NW WINDS EARLY IN THE MORNING TO QUICKLY EASE, THEN GRADUALLY
TURN TO THE NW AND INCREASE LATE AT NIGHT.
TUESDAY AND WEDNESDAY: A STORM SYSTEM WILL IMPACT THE SOUTHEAST
U.S LATE TUESDAY INTO EARLY WEDNESDAY, WITH THE PRIMARY LOW
PASSING WELL OFFSHORE. AT THE SAME TIME, HIGH PRESSURE WILL BE
LOCATED WELL TO OUR NORTH. THE PRESSURE GRADIENT BETWEEN THESE
SYNOPTIC FEATURES WILL BE VERY ELEVATED. EXPECT STRONG AND GUSTY
WINDS RAPIDLY RAMPING UP TUESDAY MORNING AND PERSISTING INTO
WEDNESDAY. THERE COULD BE A BRIEF PERIOD OF GALE CONDITIONS
TUESDAY NIGHT, MAINLY FOR THE CHARLESTON WATERS AND GA WATERS
BEYOND 20 NM. AT LEAST SMALL CRAFT ADVISORIES WILL BE NEEDED
WITH A POSSIBILITY FOR GALE WATCHES/WARNINGS. BOTH WINDS AND
SEAS START TO TREND LOWER WEDNESDAY AFTERNOON, CONTINUING INTO
THE OVERNIGHT HOURS. SEAS LOOK TO PEAK EARLY WEDNESDAY MORNING,
5-8 FT FOR THE WATERS WITHIN 20 NM AND 8-12 FT FOR THE GA WATERS
BEYOND 20 NM. THOUGH, THEY'LL BE SLOWER TO SUBSIDE INTO
WEDNESDAY NIGHT. FINALLY, MARINERS SHOULD BE ALERT THAT SOME
WINTER PRECIPITATION COULD FALL OVER THE COASTAL WATERS TUESDAY
NIGHT INTO WEDNESDAY MORNING, REDUCING VISIBILITIES TO 1 NM OR
LESS AT TIMES.
CLIMATE
RECORD LOW TEMPERATURES:
THURSDAY, JANUARY 23:
KCHS: 19/1985
KCXM: 24/2003
KSAV: 19/1960
RECORD SNOWFALL:
TUESDAY, JANUARY 21:
KCHS: T/1984*
KSAV: 0.2/1910
WEDNESDAY, JANUARY 22:
KCHS: T/2022*
KSAV: T/2011*
* A TRACE IS NOT CONSIDERED A RECORD IN TERMS OF THE DAILY
CLIMATE. TRACE AMOUNTS SHOWN ABOVE ARE MORE FOR INFORMATION OF
WHEN THE LAST INSTANCE OF SNOW OCCURRED ON THE LISTED DATE.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
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