FXUS62 KCHS 221145 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 645 AM EST Thu Jan 22 2026
.WHAT HAS CHANGED...
The aviation section has been updated for the 12Z Thursday TAF issuance.
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.KEY MESSAGES...
- 1) Widespread precipitation is expected to occur this
weekend, bringing the potential for a winter weather event across portions of the region.
- 2) Very cold temperatures will occur early next week.
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.DISCUSSION...
KEY MESSAGE 1: Widespread precipitation is expected to occur this weekend, bringing the potential for a winter weather event across portions of the region.
Focus on the forecast remains the potential for winter weather across portions of southeast South Carolina and Georgia this weekend. There has not been any drastic shifts with this forecast cycle, with high uncertainty remaining in the potential extent and magnitude of any winter weather. Strong high pressure will wedge south into the region Saturday and Saturday night. Then the feature of interest will be an area of low pressure progged to develop somewhere over/near the Gulf coast states which will track northeast over or near the local area Sunday before the main cold front swings through Sunday night.
As has been the recent trend, the GEFS favors a more prominent wedge, with colder temperatures and a resulting higher threat for a window of freezing rain over portions of the area. Meanwhile, the ENS and GEPS lean on the warmer side as the aforementioned low pressure tracks more inland over the area, keeping most of the winter weather threat over the Midlands and Upstate, and a predominately rain forecast over southeast South Carolina and southeast Georgia. Ultimately, the question will be the strength of the wedge and the track of passing low pressure. Typically, the wedge holds stronger than what most models would indicate, so this will certainly be a critical feature we will need to pay close attention to. It's also worth noting that the main axis of precipitation could remain oriented to our west when temperatures are coldest, so it could be a fairly limited potential window and spatial extent.
The main time period of concern would be Saturday evening into Sunday morning, with highest probabilities of accumulating ice roughly along and west of a line from Moncks Corner to Walterboro to Sylvania and Millen. In these locations, latest NBM probabilities indicate a 30-50% chance for freezing rain >0.01", with a 10-20% for >0.25". Probabilities decrease further east and towards the coast. Again, there remains high uncertainty in the magnitude and extent of potential winter weather, however it does continue to look like freezing rain would be the primary threat as the freezing or sub- freezing layer near the surface is very shallow with a prominent warm nose above.
Precipitation should come to an end Sunday night into early Monday with passage of the cold front. There could be a brief overlap with precip and colder temperatures, resulting in some lingering p-type concerns, but a lesser threat.
KEY MESSAGE 2: Very cold temperatures will occur early next week.
Strong high pressure will usher arctic air into the region Monday night into Tuesday morning, which should then linger through early week before airmass modification takes shape. As a result, low temps are forecast to dip into the teens west of I-95 and across much of the Francis Marion Forest while low to mid 20s are anticipated along the coast Tuesday morning. These temps in combination with a north/northeast wind generally in the 5-10 mph range could result in widespread wind chill values in the mid-upper teens. A Cold Weather Advisory could eventually be needed for the entire area across Southeast South Carolina and Southeast Georgia.
Latest guidance has trended slightly warmer Tuesday night into early Wednesday as weak high pressure centered just north of the local area slides east and south, becoming positioned along the Mid- Atlantic and Southeast coastal areas. Although a radiational cooling setup remains, some clouds enter the local area late night and could limit overnight lows to the low-mid 20s inland and upper 20s/lower 30s near the coast. Additionally, the pressure gradient appears weaker with high pressure centered closer to the area, suggesting little wind chill. Although changes in the synoptic pattern will have impacts to overnight lows, especially being several days out, conditions appear less supportive for a Cold Weather Advisory compared to the previous night/morning.
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.AVIATION /12Z THURSDAY THROUGH MONDAY/...
VFR conditions will prevail at CHS/JZI/SAV terminals through 06Z Friday.
Extended Aviation Forecast: VFR conditions are expected at CHS/JZI/SAV terminals through Friday. Periods of MVFR and/or IFR conditions are possible at all terminals this weekend as a storm system impacts the area. There is also a threat for a mix of frozen precip late Saturday night into Sunday, primarily at CHS/JZI terminals.
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.MARINE...
Today and Tonight: High pressure centered northwest of the region will gradually slide east as the day progresses, favoring a weak pressure gradient across local waters and wind/seas that remain well below Small Craft Advisory levels through the period. In general, northerly winds around 10 kt or less will become more directly onshore and weaken late day and tonight. Seas will slowly build about a foot during the next 24 hours, generally up to 3-4 ft (largest beyond 15nm from the coast).
Friday through Tuesday: Quiet marine conditions continue for much of Friday prior to a cold front advancing across local waters Friday night. Strong cold air advection and enhanced pressure gradient across local waters support deteriorating conditions across all local waters Friday night, possibly reaching Small Craft Advisory levels across all coastal waters by daybreak Saturday. Conditions should continue to deteriorate during the weekend as low pressure attempts to develop near the cold front offshore while wedging occurs inland. Guidance indicates solid Small Craft Advisory conditions across most waters Saturday into Sunday with even the possibility of low-end gusts to gale force across northern South Carolina waters during the peak of the event. 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 most waters Monday, supporting the potential for Small Craft Advisories through late day across nearshore waters (except for the Charleston Harbor) and into Tuesday across outer Georgia waters.
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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 Friday to restore full service.
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None. SC...None. MARINE...None.
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DPB/ETM