634
FXUS62 KCHS 171149
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
649 AM EST SAT JAN 17 2026
WHAT HAS CHANGED
THE AVIATION SECTION HAS BEEN UPDATED FOR THE 12Z TAF ISSUANCE.
CONFIDENCE REMAINS LOW IN REGARD TO A WINTRY MIX, INCLUDING
SNOWFALL ACCUMULATION WEST OF I-95 SUNDAY WHILE CONFIDENCE IS
HIGH FOR COLD MORNING LOWS MONDAY, TUESDAY AND WEDNESDAY MORNING.
KEY MESSAGES
- 1) POTENTIAL FOR A RAIN/SNOW MIX SATURDAY NIGHT INTO SUNDAY
AS A COASTAL LOW DEVELOPS OVER THE ATLANTIC.
- 2) COLD TEMPERATURES IN THE LOW TO MID 20S (UPPER 20S ALONG
THE COAST) POSSIBLE MONDAY, TUESDAY, AND WEDNESDAY MORNING.
DISCUSSION
KEY MESSAGE 1: POTENTIAL FOR A RAIN/SNOW MIX SATURDAY NIGHT
INTO SUNDAY AS A COASTAL LOW DEVELOPS OVER THE ATLANTIC.
A HIGH-AMPLITUDE TROUGH IS EXPECTED TO DIG ACROSS THE MIDWEST AND
DEEP SOUTH, THEN PIVOT ACROSS THE EAST CONUS, HELPING FORCE A STRONG
COLD FRONT OFFSHORE SATURDAY EVENING, WHICH THEN BECOMES THE PRIMARY
FOCAL POINT OF CYCLOGENESIS OFF THE SOUTHEAST AND MID-ATLANTIC COAST
SUNDAY MORNING. 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 SATURDAY NIGHT INTO SUNDAY, BEFORE
DIMINISHING AND/OR SHIFTING OFFSHORE SUNDAY AFTERNOON. THE MAIN
ISSUE WILL CONTINUE TO FOCUS ON A RAIN-SNOW MIX POSSIBILITY LOCALLY
AS STRONG COLD AIR ADVECTION COMMENCES POST FROPA SUNDAY MORNING,
SUPPORTING BELOW FREEZING TEMPERATURES OFF THE SFC WITH THERMAL
PROFILES INCREASINGLY FAVORABLE FOR RAIN MIXING WITH AND/OR POSSIBLY
CHANGING TO ALL SNOW AS PRECIPITATION EXITS THE AREA.
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 ARE LIKELY TO REMAIN ABOVE THE FREEZING MARK
UNDER WIDESPREAD CLOUD COVER THROUGH THE ENTIRE EVENT, EVEN ACROSS
FAR INLAND AREAS WHERE SNOWFALL ACCUMULATION IS POSSIBLE. PROFILES
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 SUNDAY MORNING. HOWEVER, THE BEST COMBINATION OF
MOISTURE AND FORCING APPEARS LIMITED TO HOURS AROUND DAYBREAK SUNDAY
INTO LATE MORNING SUNDAY, AS SOUNDINGS INDICATE MOISTURE TO BECOME
QUICKLY REMOVED FROM THE -10 TO -20C LAYER DURING DAYLIGHT HOURS.
WIDESPREAD CLOUDS WILL ATTEMPT TO KEEP SFC TEMPS COOLER THROUGH LATE
MORNING HOURS, BUT A RAIN/SNOW MIX EVENT STILL APPEARS LIMITED GIVEN
THE LACK OF SUB-FREEZING SFC TEMPS AND DEPARTING LOW-MID LVL
MOISTURE AS DAYTIME WARMING BEGINS. BY AROUND NOON, THE CHANCES FOR
A RAIN/SNOW MIX WITH ANY ACCUMULATION IS LIKELY COMING TO AN END.
ALTHOUGH GROUND TEMPERATURES ARE LIKELY TO REMAIN RATHER WARM,
LOCALIZED, HEAVIER SNOWFALL RATES COULD SUPPORT A QUICK DUSTING TO
POSSIBLY AS HIGH AS 0.5" BEFORE A QUICK MELTING OCCURS ACROSS THE
INLAND AREA NOTED ABOVE. NBM SNOWFALL PROBABILITIES FOR 1" CONTINUE
TO RUN AS HIGH AS 15-25% ACROSS THE NOTED AREA, BUT THIS SCENARIO
LOOKS UNLIKELY GIVEN OVERALL SNOWFALL PROBABILITIES AND APPEARS TO
BE A WORST-CASE SCENARIO FOR PLANNING PURPOSES. THE RAIN/SNOW MIX
COULD REACH AS FAR EAST AS THE I-95 CORRIDOR, BUT AN ALL RAIN EVENT
IS FAVORED ALONG COASTAL AREAS.
AS FOR IMPACTS, WINTER WEATHER IMPACTS FROM THIS SYSTEM STILL REMAIN
ON THE LOW SIDE. THE LATEST PROBABILISTIC WINTER STORM SEVERITY
INDEX (WSSI-P) ADVERTISES A 15-30% CHANCE OF MINOR IMPACTS, SO
EXERCISE CAUTION IF TRAVEL IS NECESSARY AS A FEW SLICK SPOTS COULD
OCCUR, ESPECIALLY ON BRIDGES OR ELEVATED SURFACES. A LOW-END RISK
FOR SOME PATCHY BLACK ICE COULD LINGER INTO SUNDAY NIGHT, BUT
LINGERING WINDS AND LOWERING DEWPTS SHOULD HELP DRY ROADS OUT PRIOR
TO THE ONSET OF FREEZING TEMPS SUNDAY NIGHT.
KEY MESSAGE 2: COLD TEMPERATURES IN THE LOW TO MID 20S (UPPER
20S ALONG THE COAST) POSSIBLE MONDAY, TUESDAY, AND WEDNESDAY
MORNING.
SECONDARY UPPER LEVEL SHORTWAVE DIGS ACROSS THE OHIO RIVER VALLEY
INTO MONDAY, DRAGGING AN ATTENDANT COLD FRONT TOWARD THE REGION.
STRONG HIGH PRESSURE OVER THE NORTHERN PLAINS THEN BUILDS ACROSS THE
AREA IN ITS WAKE, RESULTING IN AN INFLUX OF CAA. THIS WILL RESULT IN
NOTABLY COLDER TEMPERATURES MONDAY, TUESDAY, AND WEDNESDAY MORNING.
CURRENTLY HAVE MORNING LOWS IN THE LOW TO MID 20S, WITH AREAS ALONG
THE COAST NEAR/JUST BELOW FREEZING. DESPITE WINDS REMAINING ON THE
LIGHTER SIDE, WILL SEE WIND CHILLS PLUMMET INTO TEENS TO LOWER 20S
ACROSS SOME OF OUR INTERIOR COUNTIES MONDAY MORNING, WHICH MAY
PROMPT THE NEED FOR A COLD WEATHER ADVISORY IN THE COMING SHIFTS.
SIMILAR CONDITIONS ARE EXPECTED TUESDAY, WITH CONFIDENCE IN HOW
WIDESPREAD THESE VALUES WILL BE DECREASING AS WE HEAD INTO
WEDNESDAY. OTHERWISE, EXPECT AFTERNOON HIGHS TO REMAIN SEASONALLY
COOL, AS TEMPERATURES ONLY RISE INTO THE UPPER 40S TO 50S.
AVIATION /12Z SATURDAY THROUGH WEDNESDAY/
VFR CONDITIONS WILL PREVAIL AT CHS/SAV/JZI TERMINALS THROUGH AT
LEAST 06Z SUNDAY, BUT A COLD FRONT WILL BRING LIGHT RAIN AND
POSSIBLY MVFR CIGS AT ALL SITES APPROACHING 12Z SUNDAY. AT THIS
TIME, HAVE INTRODUCED LIGHT RAIN AND 6SM VSBYS AT ALL TERMINALS
STARTING AT 09Z SUNDAY.
EXTENDED AVIATION FORECAST: A PERIOD OF FLIGHT RESTRICTIONS IN
SHOWERS IS LIKELY SUNDAY MORNING AT ALL THREE TERMINALS.
MARINE
THERE ARE NO CONCERNS TONIGHT THROUGH TODAY, BUT WINDS ARE
EXPECTED TO INCREASE SUNDAY IN WAKE OF A COLD FRONT SHIFTING
OFFSHORE AND LOW PRESSURE DEVELOPING OFF THE SOUTHEAST/MID-
ATLANTIC COAST. WINDS GUSTS COULD APPROACH 20-25 KT, HIGHEST
ACROSS OUTER GEORGIA WATERS LATE SUNDAY MORNING INTO THE
AFTERNOON. ADDITIONALLY, SEAS WILL ALSO BUILD AWAY FROM THE
COAST, LARGEST ACROSS OUTER GEORGIA WATERS (4-6FT) SUNDAY. A
SMALL CRAFT ADVISORY COULD EVENTUALLY BE NEEDED LATE SUNDAY
MORNING AND AFTERNOON.
MONDAY ONWARD: HIGH PRESSURE GRADUALLY BUILDS ACROSS OUR AREA
HEADING INTO THE NEW WEEK, ALLOWING QUIET CONDITIONS TO PREVAIL
ACROSS OUR WATERS. NORTHWESTERLY WINDS MAY BECOME A TAD BREEZY ON
TUESDAY, WITH GUSTS UP TO 20 KTS POSSIBLE THROUGH THE AFTERNOON.
CHS WATCHES/WARNINGS/ADVISORIES
GA...NONE.
SC...NONE.
MARINE...NONE.
DPB/SST
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