FXUS62 KCHS 211145 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 645 AM EST Wed Jan 21 2026
.WHAT HAS CHANGED...
The aviation section has been updated for the 12Z TAF issuance. Cold temperatures are likely this morning and remain in key message 1. The potential for a winter weather event remains addressed in key message 2. Cold temperatures remain addressed in key message 3.
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.KEY MESSAGES...
- 1) Cold temperatures in the mid to upper 20s across inland
areas this morning.
- 2) Widespread precipitation is expected to occur this
weekend, bringing increasing potential for a multi-day winter weather event across portions of the region.
- 3) Very cold temperatures will occur early next week.
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.DISCUSSION...
KEY MESSAGE 1: Cold temperatures in the mid to upper 20s across inland areas this morning.
Dry high pressure centered across the Mid-Atlantic States tonight will slowly slip offshore across the western Atlantic mid-late morning, supporting a light northerly wind tonight to tip more north- northeast approaching daybreak. Strong radiational cooling under clear skies will support low temps in the mid 20s, coldest along and west of I-95 and north of I-16 where little to no cirrus impacts maximum radiational cooling for the night. Winds will remain light/calm in these areas late night, indicating little in the way of wind chill values below these forecasted low temperatures. A Cold Weather Advisory is not expected at this time.
KEY MESSAGE 2: Widespread precipitation is expected to occur this weekend, bringing increasing potential for a multi-day winter weather event across portions of the region.
Focus for the week will continue be on the potential winter weather event impacting at least portions of southeast South Carolina and southeast Georgia this weekend into early next week. Strong, cold high pressure will wedge down into the region through the weekend, with low pressure expected to develop off the Southeast coast. Increasing isentropic ascent will lead to rain spreading into the area on Saturday, then concern increases later Saturday into Saturday night for wintry weather over parts of the area as cold air settles in. Model soundings remain consistent in indicating a prominent warm nose centered around 850 mb with around freezing/sub- freezing temps developing closer to the surface. This would suggest freezing rain could become the more dominant p-type, especially inland, with little chance for snow which jives with most model guidance and probabilities. There is question in how close to the coast and south the freezing temperatures will reach.
Temperatures will remain very chilly through the day Sunday, but there is still quite a spread in guidance regarding how cold it could stay. Most areas should "warm" enough during the daytime hours to transition most precipitation back over to rain. Over the far interior, p-type concerns could linger longer.
There remains uncertainty regarding the end of the precipitation. There is a pretty even split among ensemble members per cluster analysis on scenarios. One cluster, comprised of mostly GFS and Canadian members, would indicate a slower exit to the upper wave, which in turn could keep precip around a bit longer into Monday. While another cluster, majority Euro members, hints at a faster exit and end to the precip. Any lingering precipitation Sunday night and Monday morning could be in the form of freezing rain, especially north of I-16, given high likelihood of sub-freezing temperatures and temperature profiles.
This event has potential to bring accumulating ice to the area. Latest NBM shows the probability for 48 hour freezing rain accumulation >0.01" in the 50-80% range largely north of I-16. Looking at the probabilities for >0.25" peaks around 30-40% roughly along and west of a line from Moncks Corner to Walterboro to Sylvania and Millen. Winter Weather Watches and/or Advisories will be possible in the coming days.
The Probabilistic Winter Storm Severity Index (WSSI-P) continues to show chances of minor winter storm impacts across the entire area, with even a 20-40% chance of moderate impacts especially north of I- 16.
KEY MESSAGE 3: Very cold temperatures will occur early next week.
Strong high pressure will usher arctic air into the region Monday night into Tuesday morning, which then lingers through early week before the airmass modifies/warms during the second half of the week. As a result, low temps are forecast to dip into the teens west of I-95 with low to mid 20s along the coast Tuesday morning and Wednesday morning. These temps in combination with a north/northeast wind around 10 mph across the region could result in widespread wind chill values in the teens. Cold Weather Advisories could eventually be needed.
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.AVIATION /12Z WEDNESDAY THROUGH SUNDAY/...
VFR conditions will prevail at CHS/JZI/SAV terminals through 12Z Thursday.
Extended Aviation Forecast: VFR conditions are expected at CHS/JZI/SAV terminals through Friday. Periods of MVFR and/or IFR conditions possible with a rain and/or mix of frozen precip over the weekend.
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.MARINE...
Today and Tonight: High pressure centered across the Mid-Atlantic states early morning will gradually slide east across the western Atlantic this afternoon and overnight. The setup will favor quiet marine conditions across local waters with northeast winds up to 10- 15 kt early day trending weaker during the afternoon and night while tipping back to the north-northwest. Seas will generally range between 1-3 ft nearshore to 3-4 ft across outer Georgia waters.
Thursday and Friday: Quiet marine conditions will persist into late week while weak high pressure lingers across the Southeast ahead of a front approaching inland. In general, a north/northeast wind up to around 10 kt will be common across most waters. Seas should range between 2-3 ft nearshore to 3-4 ft across outer Georgia waters.
Friday night through Monday: This is period of greatest concern in regards to deteriorating wind/sea conditions. A cold front will approach the Southeast by the weekend, likely shifting offshore by Friday evening with strong cold air advection in its wake. Conditions will begin to deteriorate across local waters as a result Friday night, possibly reaching Small Craft Advisory levels across South Carolina waters after midnight Friday night and across Georgia waters by around daybreak Saturday. Conditions should continue to deteriorate during the weekend as low pressure attempts to develop near the cold front positioned offshore, with guidance suggesting a solid Small Craft Advisory event across all waters this weekend and the possibility of low-end gusts to gale force as cold air advection promotes ample mixing into enhanced low-lvl wind fields during the peak of the event Saturday night into Sunday morning. Northeast winds gusting up to 25-30 kt appear common across most waters while seas build upwards to 7-10 ft (largest away from the coast). High seas could linger across outer Georgia waters into Monday, supporting a longer duration Small Craft Advisory into early next week.
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.EQUIPMENT...
The Beaufort/Green Pond NOAA Weather Radio transmitter (WXJ-23) is operating at low power with diminished service. Repairs are scheduled to be made today or Thursday to restore full service.
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None. SC...None. MARINE...None.
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DPB/ETM