050
FXUS62 KCHS 131102
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
602 AM EST TUE JAN 13 2026
WHAT HAS CHANGED
THE FIRST KEY MESSAGE WAS UPDATED TO MENTION ONLY THIS
AFTERNOON FOR LOW RELATIVE HUMIDITY VALUES. FOR THE SECOND KEY
MESSAGE, WIND GUSTS SHOULD REMAIN WITHIN SMALL CRAFT ADVISORY
LEVELS THURSDAY INTO THURSDAY EVENING. THE RISK FOR GALE FORCE
WIND GUSTS HAS DIMINISHED.
KEY MESSAGES
1) DRY HIGH PRESSURE WILL REMAIN ACROSS SOUTHEAST GEORGIA AND
SOUTH CAROLINA TODAY, YIELDING LOW RELATIVE HUMIDITY VALUES THIS
AFTERNOON.
2) DANGEROUS FIRE WEATHER AND MARINE CONDITIONS POSSIBLE AS
GUSTY WINDS AND LOW HUMIDITY VALUES ARRIVE BEHIND A MOSTLY DRY
COLD FRONT THURSDAY INTO FRIDAY.
3) VERY COLD TEMPERATURES WILL OCCUR FRIDAY MORNING, WITH LOWS
IN THE UPPER TEENS TO LOWER 20S AWAY FROM THE BEACHES.
DISCUSSION
KEY MESSAGE 1: DRY HIGH PRESSURE WILL REMAIN ACROSS SOUTHEAST
GEORGIA AND SOUTH CAROLINA TODAY, YIELDING LOW RELATIVE HUMIDITY
VALUES THIS AFTERNOON.
DRY SFC HIGH PRESSURE WILL LINGER ACROSS THE SOUTHEAST U.S.
TODAY. FORECAST SOUNDINGS INDICATE THAT MIXING WILL RANGE
BETWEEN 2.5 TO 3 KFT THIS AFTERNOON. AS MIXING BEGINS, SFC
DEWPOINTS SHOULD REMAIN IN THE 20S THROUGH MID-DAY. HOWEVER,
WEAK SOUTHWEST WINDS MAY RESULT IN A SLOW INCREASE IN DEWPOINTS
FROM SOUTH AND NEAR THE COAST, INCREASING INTO THE 30S. MINIMUM
RH VALUES SHOULD OCCUR DURING THE EARLY AFTERNOON HOURS, BEFORE
THE DEWPOINT RECOVERY. MIN RH VALUES ARE FORECAST TO RANGE FROM
THE MID 20S INLAND TO THE MID 30S ALONG THE COAST. HIGH
TEMPERATURES ARE FORECAST TO RANGE AROUND 10 DEGREES WARMER THAN
VALUES REACHED ON MONDAY, GENERALLY IN THE LOW 60S.
KEY MESSAGE 2: DANGEROUS FIRE WEATHER AND MARINE CONDITIONS
POSSIBLE AS GUSTY WINDS AND LOW HUMIDITY VALUES ARRIVE BEHIND A
MOSTLY DRY COLD FRONT THURSDAY INTO FRIDAY.
ON THURSDAY A REX BLOCK WILL BE ESTABLISHED OVER THE WESTERN
UNITED STATES ALLOWING FOR A LONG WAVE TROUGH AXIS TO AMPLIFY
ACROSS THE EASTERN UNITED STATES. IN THE MID-LEVELS OF THE
ATMOSPHERE, A CLOSED MID-LEVEL LOW WILL BE MOVING EAST ACROSS
THE GREAT LAKES WITH A STRONG PUSH OF LOWER HEIGHTS APPROACHING
THE AREA FROM THE WEST (120 M HEIGHT FALLS IN 12 HRS). THIS
MAGNITUDE OF DCVA/ HEIGHT FALLS IS RATHER IMPRESSIVE, BUT
PRECIPITATION CHANCES ARE LIMITED (<15%) WITH THE SURFACE COLD
FRONT THURSDAY MORNING/ AFTERNOON. THERE ARE SEVERAL REASONS FOR
THIS. THE MAIN REASON BEING THE WEDNESDAY WAVE. THIS WAVE WILL
BE MOVING AWAY EARLY THURSDAY WITH THE LFQ OF THE SUBTROPICAL
JET STREAK MOVING OFF OF THE COAST. DURING THIS TYPE OF SETUP,
MOST OF THE PRECIPITATION GETS GOING OFF OF THE SOUTH CAROLINA/
NORTH CAROLINA COAST.
BEHIND THE SURFACE COLD FRONT, STRONG LOW LEVEL CAA WILL TAKE
HOLD WITH 850 MB TEMPERATURES DROPPING FROM 0 DEGREES C TO -8
DEGREES C. THIS, IN COMBINATION WITH PEAK MIXING AND DOWNSLOPE
FLOW IN THE LOW AND MID LEVELS, WILL LIKELY RESULT IN WIND GUSTS
THURSDAY AFTERNOON ON THE HIGHER END OF THE GUIDANCE ENVELOPE,
WITH 25 TO 30 MPH GUSTS LIKELY, WITH SOME GUSTS TO 35 MPH
POSSIBLE OVER LAND. A LAKE WIND ADVISORY WILL LIKELY BE
NECESSARY WITH PROBABILITIES OF REACHING 25 KT AROUND 55%.
ADDITIONALLY, DEWPOINTS WILL RAPIDLY FALL BEHIND THE COLD FRONT
ALLOWING RELATIVE HUMIDITY VALUES TO APPROACH 25%. IT SHOULD BE
NOTED THAT THE WAMBAW AND GLISSONS POND RAWS SITES HAVE BOTH
HAD FUEL MOISTURE VALUES IN THE SINGLE DIGITS SUNDAY AND MONDAY
AFTERNOONS.
SURFACE HIGH PRESSURE WILL SETTLE OVERHEAD FRIDAY, WITH
DEWPOINTS LIKELY MIXING OUT TO NEAR THE SINGLE DIGITS IN THE
AFTERNOON. THE LATEST LREF PROBABILITIES SHOW A 50 - 70% CHANCE
OF RH VALUES LESS THAN 25% AWAY FROM THE IMMEDIATE COAST. WINDS
WILL BE MUCH WEAKER FRIDAY THOUGH GIVEN THE PROXIMITY OF THE
SURFACE HIGH PRESSURE TO COASTAL SOUTH CAROLINA AND GEORGIA.
KEY MESSAGE 3: VERY COLD TEMPERATURES WILL OCCUR FRIDAY
MORNING, WITH LOWS IN THE UPPER TEENS TO LOWER 20S AWAY FROM THE
BEACHES.
SURFACE HIGH PRESSURE NOW LOOKS TO MOVE EAST FASTER, OR ALLOW
WINDS TO DECOUPLE QUICKER THURSDAY NIGHT/ FRIDAY MORNING. AS
SUCH, LOW TEMPERATURES WILL LIKELY BE IN THE UPPER TEENS FOR
AREAS OF RURAL GEORGIA AWAY FROM THE COAST (AND CLOSER TO THE
SURFACE HIGH PRESSURE), AND LOW 20S FOR THE REST OF COASTAL
SOUTH CAROLINA. RIGHT AT THE BEACHES (INCLUDING THE CHARLESTON
PENINSULA), EXPECT LOWS IN THE UPPER 20S. WIND CHILL TO
TEMPERATURE SPREAD WILL LIKELY BE GREATEST THURSDAY EVENING,
WITH THE DIFFERENTIAL BECOMING LESS AND LESS AS WINDS SLACKEN BY
FRIDAY MORNING. STILL THOUGH, ENOUGH WIND IS FORECAST THAT A
COLD WEATHER ADVISORY MIGHT BE REQUIRED FOR SOME OF THE AREA
FRIDAY MORNING. RURAL GEORGIA HAS ~ A 60- 80% CHANCE OF NEEDING
A COLD WEATHER ADVISORY, WHILE COASTAL SOUTH CAROLINA AND
GEORGIA HAS ~ A 20-50% CHANCE OF NEEDING A COLD WEATHER
ADVISORY.
AVIATION /12Z TUESDAY THROUGH SATURDAY/
VFR CONDITIONS WILL PREVAIL AT CHS/JZI/SAV TERMINALS THROUGH
12Z WEDNESDAY.
EXTENDED AVIATION OUTLOOK: VFR CONDITIONS WILL CONTINUE FOR
KCHS, KJZI AND KSAV THROUGH LATE WEEK. NW WINDS COULD GUST TO
AROUND 20 KTS IN THE WAKE OF COLD FRONT.
MARINE
BROAD HIGH PRESSURE WILL REMAIN ACROSS THE MARINE ZONES TODAY
AND TONIGHT. THE PATTERN SHOULD YIELD AROUND 5 KTS OF WIND
TODAY, GRADUALLY INCREASING TO 5 TO 10 KTS TONIGHT. SEAS ARE
FORECAST TO REMAIN BETWEEN 2 TO 3 FT.
WEDNESDAY, THE MARINE ZONES WILL REMAIN BETWEEN A DEVELOPING
LOW PRESSURE SYSTEM OVER THE GULF STREAM AND A COLD FRONT OVER
THE WESTERN CAROLINAS. A WEAK GRADIENT ON THE WEST SIDE OF THE
LOW KEEPS BENIGN MARINE CONDITIONS IN PLACE DESPITE INCREASED
SHOWER CHANCES.
A STRONG COLD FRONT WILL CROSS THE AREA WEDNESDAY NIGHT.
NORTHWEST WINDS SHOULD DEVELOP IN THE WAKE OF THE FRONT, WITH
GUSTS AROUND 25 KTS ACROSS THE ATLANTIC WATERS OF GA AND SC ON
THURSDAY INTO THURSDAY EVENING. AS A RESULT, WAVE HEIGHTS WILL
BUILD DURING THE DAYLIGHT HOURS ON THURSDAY, PEAKING BETWEEN 3-5
FT ACROSS THE NEARSHORE WITH 6FT BEYOND 30 NM THURSDAY EVENING.
SMALL CRAFT ADVISORIES WILL LIKELY BE NEEDED FOR ALL MARINE
ZONES OUTSIDE THE CHS HARBOR THURSDAY AND THURSDAY EVENING. THE
CENTER OF A LARGE AREA OF HIGH PRESSURE WILL ARRIVE ON FRIDAY,
SUPPORTING WINDS AROUND 10 KTS WITH 1-2 FT SEAS. WINDS SHOULD
GRADUALLY STRENGTHEN AS A DRY COLD FRONT SWEEPS ACROSS THE
REGION ON SATURDAY, WITH GUSTY WINDS AND BUILDING SEAS, POSSIBLY
REACHING SMALL CRAFT CONDITIONS ACROSS A PORTION OF THE WATERS.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
HAINES/NED
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page