916
FXUS62 KCHS 181157
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
657 AM EST SUN JAN 18 2026
WHAT HAS CHANGED
THE AVIATION SECTION HAS BEEN UPDATED FOR THE 06Z TAF ISSUANCE.
PRECIPITATION TIMING IS A FEW HOURS DELAYED FOR DEPARTING THE AREA
SUNDAY AFTERNOON. MIXED RAIN/SNOW MIX REMAINS POSSIBLE ACROSS FAR
INLAND AREAS LATE THIS MORNING INTO EARLY AFTERNOON.
KEY MESSAGES
- 1) RISK FOR A RAIN/SNOW MIX WITH MINOR ACCUMULATIONS POSSIBLE
ACROSS FAR INLAND AREAS LATE MORNING INTO EARLY AFTERNOON AS A
COASTAL LOW DEVELOPS OVER THE ATLANTIC.
- 2) COLD TEMPERATURES IN THE LOW TO MID 20S (UPPER 20S TO
LOWER 30S ALONG THE COAST) POSSIBLE MONDAY, TUESDAY, AND
WEDNESDAY MORNING.
DISCUSSION
KEY MESSAGE 1: RISK FOR A RAIN/SNOW MIX WITH MINOR ACCUMULATIONS
POSSIBLE ACROSS FAR INLAND AREAS LATE MORNING INTO EARLY AFTERNOON
AS A COASTAL LOW DEVELOPS OVER THE ATLANTIC.
A HIGH-AMPLITUDE TROUGH IS EXPECTED TO PIVOT ACROSS THE EAST CONUS
TODAY, FORCING A STRONG COLD FRONT OFFSHORE EARLY THIS MORNING,
WHICH THEN BECOMES A FOCAL POINT OF CYCLOGENESIS OFF THE SOUTHEAST
AND MID-ATLANTIC COAST DURING THE DAY. STRONG MID-UPPER LVL FORCING
ASSOCIATED WITH H5 VORT ENERGY AND FAVORABLE DIVERGENCE IN THE RIGHT-
REAR QUADRANT OF AN H25 JET STREAK ALONG WITH AMPLE LOW-MID LVL
MOISTURE ADVECTING ACROSS THE LOCAL AREA WITHIN A SOUTHWEST FLOW
WILL SET THE STAGE FOR PRECIPITATION ACROSS THE REGION THIS MORNING
INTO EARLY AFTERNOON, BEFORE ACTIVITY DEPARTS OFFSHORE AS DRY HIGH
PRESSURE BUILDS ACROSS THE REGION FROM THE WEST. THE MAIN ISSUE
CONTINUES TO FOCUS ON THE POSSIBILITY OF A RAIN-SNOW MIX ACROSS THE
FAR INTERIOR AS STRONG COLD AIR ADVECTION COMMENCES POST FROPA AND
MOISTURE LINGERS, WITH FREEZING TEMPERATURES OFF THE SURFACE
BECOMING SOMEWHAT FAVORABLE FOR SNOW DURING A FEW HOUR PERIOD LATE
MORNING INTO EARLY AFTERNOON.
THE MAIN QUESTION CONTINUES TO FOCUS ON THE LOW-LVL THERMAL PROFILE
AND ABILITY TO MAINTAIN SNOW PRIOR TO REACHING THE SFC AND
ACCUMULATION ONCE SETTING ON WARMER GROUNDS. LATEST MODEL SOUNDINGS
INDICATE NEAR SFC TEMPS REMAINING ABOVE THE FREEZING MARK UNDER
WIDESPREAD CLOUDS THROUGH THE ENTIRE EVENT, EVEN ACROSS FAR INLAND
AREAS WHERE SNOWFALL ACCUMULATION IS POSSIBLE. SOME GUIDANCE HAS
COME IN A BIT WARMER IN REGARDS TO THE SOUNDING PROFILE OFF THE SFC
INITIALLY, SUGGESTING A DELAY TO A RAIN-SNOW MIX AND THEREFORE A
SHORTER WINDOW OF SNOWFALL ACCUMULATION MID-LATE MORNING INTO EARLY
AFTERNOON PRIOR TO MOISTURE BECOMING QUICKLY REMOVED TO THE EAST
AND OFFSHORE. PROFILES CONTINUE TO SUGGEST IT WILL TAKE AMPLE
MOISTURE IN THE DENDRITIC GROWTH ZONE FOR THE SNOW TO ACCUMULATE
ACROSS FAR INLAND ZONES WELL WEST OF THE I-95 CORRIDOR, MAINLY
ALONG A STRETCH FROM ALLENDALE COUNTY, SC TO TATTNALL COUNTY,
GA, BUT GIVEN THE SHORTER WINDOW FOR ACCUMULATION AND WARMER
GROUNDS LIKELY MELTING A GOOD PORTION OF ANY SNOW REACHING THE
SFC, A DUSTING TO PERHAPS AS MUCH AS 1/2 INCH SNOWFALL IS POSSIBLE
ACROSS THE NOTED AREA BY EARLY AFTERNOON. AN ALL RAIN EVENT IS
FAVORED FOR ALL AREAS ALONG AND EAST OF THE I-95 CORRIDOR.
WINTER WEATHER IMPACTS FROM THIS SYSTEM REMAIN ON THE LOW SIDE AS
MOST SNOWFALL ACCUMULATION IS LIKELY CONFINED TO GRASSY AREAS AND
OTHER ELEVATED SURFACES SUCH AS ROOF TOPS. ISOLATED SLICK SPOTS
COULD OCCUR ON BRIDGES AND OVERPASSES, BUT SIGNIFICANT TRAVEL
IMPACTS ARE NOT EXPECTED AT THIS TIME GIVEN TEMPERATURES WILL
LARGELY REMAIN ABOVE FREEZING.
KEY MESSAGE 2: COLD TEMPERATURES IN THE LOW TO MID 20S (UPPER
20S TO LOWER 30S ALONG THE COAST) POSSIBLE MONDAY, TUESDAY, AND
WEDNESDAY MORNING.
CAA BEGINS TO INFILTRATE THE REGION SUNDAY NIGHT IN THE WAKE OF A
DEPARTING SFC LOW AND SHORTWAVE ALOFT, RESULTING IN NOTABLY COOLER
TEMPERATURES TO START THE WEEK. CURRENTLY HAVE MORNING LOWS IN THE
MID 20S INLAND TO LOW 30S ALONG THE COAST. WHILE WESTERLY WINDS LOOK
TO REMAIN RELATIVELY LIGHT DURING THE EARLY MORNING HOURS, THINK
CLEAR SKIES AND EFFICIENT RADIATIONAL COOLING COULD RESULT IN WIND
CHILLS DROPPING INTO THE UPPER TEENS TO LOWER 20S. IN TERMS OF
PROBABILITIES, LATEST ENSEMBLE GUIDANCE SUGGEST AROUND A 30-40%
CHANCE OF SEEING WIND CHILLS LESS THAN 20 DEGF (COLD WEATHER
ADVISORY LEVELS) IN AREAS WEST OF I-95. GIVEN THAT THESE
PROBABILITIES CONTINUE TO WAIVER, HAVE OPTED TO FORGO ANY HEADLINES
FOR THE TIME BEING, ALLOWING THE COMING SHIFTS TO MONITOR TRENDS AND
REFINE VALUES AS NEEDED.
EXPECT SIMILAR CONDITIONS TO PREVAIL TUESDAY AND WEDNESDAY MORNING
IN THE WAKE OF A STRONG COLD FRONT AND BUDDING SFC HIGH PRESSURE.
AGAIN, WITH WINDS REMAINING RELATIVELY WEAK, EXPECT DROPPING WINDS
CHILLS TO MAINLY BE A FACTOR OF EFFICIENT RADIATIONAL COOLING.
ENSEMBLE GUIDANCE CONTINUES TO ONLY SUGGEST AROUND A 20-40% CHANCE
OF REACHING COLD WEATHER ADVISORY LEVELS, KEEPING OVERALL CONFIDENCE
RATHER LOW. NONETHELESS, WHETHER WE HIT HEADLINE CRITERIA OR NOT,
STILL WANT TO ENCOURAGE FOLKS TO TAKE NECESSARY PRECAUTIONS FOR
THESE COLD TEMPERATURES. THIS CAN INCLUDE DRESSING IN WARM LAYERS,
LIMITING TIME OUTSIDE, AND INSULATING/EXPOSING PIPES TO HEATED AIR.
OTHERWISE, EXPECT AFTERNOON HIGHS TO REMAIN SEASONALLY COOL, AS
TEMPERATURES ONLY RISE INTO THE UPPER 40S TO 50S.
AVIATION /12Z SUNDAY THROUGH THURSDAY/
TEMPO MVFR CONDITIONS ARE POSSIBLE IN 12-14Z SUNDAY TIMEFRAME AT
CHS/JZI AND 12-13Z SUNDAY TIMEFRAME AT SAV. IFR CONDITIONS THEN
PREVAIL AT ALL TERMINALS, STARTING AROUND 13Z SUNDAY AT SAV AND
AROUND 14Z SUNDAY AT CHS/JZI, LIKELY PERSISTING UNTIL 20-21Z SUNDAY
AFTERNOON. GUSTY NORTHWEST WINDS UP TO 15-20 KT SHOULD HELP IMPROVE
CONDITIONS TO MVFR AT ALL TERMINALS FOR A FEW HOURS LATE AFTERNOON.
DRIER AIR THEN ENTERS WITH HIGH PRESSURE BUILDING FROM THE WEST,
LEADING TO VFR CONDITIONS RETURNING AT ALL TERMINALS AROUND 00Z
MONDAY. VFR CONDITIONS THEN PERSIST THROUGH 12Z MONDAY.
EXTENDED AVIATION FORECAST: ANY FLIGHT RESTRICTIONS LOOK TO END
SUNDAY AFTERNOON, ALLOWING VFR CONDITIONS TO RETURN FOR THE
REMAINDER OF THE EXTENDED FORECAST.
MARINE
TODAY AND TONIGHT: STRONG COLD AIR ADVECTION ASSOCIATED WITH HIGH
PRESSURE BUILDING ACROSS THE REGION IN WAKE OF A FRONT DEPARTING
WELL OFFSHORE WILL FAVOR GUSTY NORTHWEST WINDS UPWARDS TO 25-30 KT
AND SEAS AS LARGE AS 3-6 FT ACROSS GEORGIA WATERS TODAY INTO THE
EVENING. SMALL CRAFT ADVISORIES REMAIN IN EFFECT ACROSS GEORGIA
WATERS AS A RESULT, BUT CONDITIONS WILL BEGIN TO IMPROVE LATE DAY AS
THE PRESSURE GRADIENT WEAKENS WITH HIGH PRESSURE CONTINUING TO BUILD
ACROSS THE REGION. AS A RESULT, THE SMALL CRAFT ADVISORY ACROSS
NEARSHORE WATERS LIKELY ENDS MID-LATE AFTERNOON TODAY, FOLLOWED BY
OUTER GEORGIA WATERS SHORTLY AFTER MIDNIGHT TONIGHT.
MONDAY ONWARD: HIGH PRESSURE GRADUALLY BUILDS ACROSS OUR AREA
HEADING INTO THE NEW WEEK, KEEPING CONDITIONS QUIET ACROSS OUR
WATERS. NORTHWESTERLY WINDS MAY BECOME A TAD BREEZY ON TUESDAY
THOUGH, WITH GUSTS UP TO 20 KTS POSSIBLE THROUGH THE AFTERNOON.
OTHERWISE, EXPECT WAVE HEIGHTS TO TREND UPWARDS ON WEDNESDAY AS
SWELLS MOVE IN FROM THE ATLANTIC.
CLIMATE
SNOWFALL RECORDS FOR JANUARY 18:
KCHS: 0.4/1977
KSAV: 1.0/1893
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EST THIS AFTERNOON FOR AMZ354.
SMALL CRAFT ADVISORY UNTIL 1 AM EST MONDAY FOR AMZ374.
DPB/SST
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