FXUS62 KCHS 091123 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 623 AM EST Fri Jan 9 2026
.SYNOPSIS...
High pressure will extend across the region through Saturday. A cold front will push offshore Sunday morning followed by another area of high pressure. Another cold front could impact the area by the middle of next week.
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.NEAR TERM /THROUGH TONIGHT/...
Today: Aloft, high amplitude ridging will extend up the Eastern Seaboard associated with a large anticyclone situated across the southeastern Gulf. At the surface, the forecast area will become positioned within the southwestern periphery of high pressure off the New England and ahead of a cold front that stretches from the OH Valley to the lower MS Valley. The day is expected to start with widespread very low stratus and dense fog which will take some time to mix out and lift. It will likely take until late morning or even early afternoon until we start to see a decent amount of sun. Once insolation begins, the area should warm up rapidly within the large warm sector ahead of the front. In fact we could make a run for daily records (see Climate section below). Inland areas should warm up solidly into the mid to upper 70s, with a few low 80s even possible across interior southeast GA south of I-16. Along the coastal corridor, temperatures will be a bit more problematic as fog could linger across the nearshore coastal waters and periodically penetrate inland along the coast within the light southerly flow. Some coastal locations could struggle to get out of the mid 60s depending on how the marine fog evolves.
Tonight: The overall setup will remain the same with the forecast area positioned within the warm sector of the front to the west. Any precipitation will remain displaced well to the west along the front, keeping the forecast dry through the overnight. As a result, the main forecast issue will once again be fog. Model guidance suggests that the main source will be marine/sea fog across the coastal waters that could advect onshore within a stronger low-level southerly wind field. Dense fog could again become an issue for much of the area and Dense Fog Advisories could be needed. Temperatures will be very mild, with lows around 60 for most of the area (right around normal highs for early January).
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.SHORT TERM /SATURDAY THROUGH MONDAY/...
On Saturday, a potent upper ridge axis will extend from the eastern Gulf northeast through the Bahamas while surface high pressure extends across much of the western Atlantic. A cold front will approach the forecast area from the west late in the afternoon, moving through the area early Sunday morning. Strong southerly flow will advect in an unseasonably warm and moist airmass on Saturday. High temps on Saturday could approach records at KCHS and KSAV. Inland southeast GA could reach the lower 80s while most other areas inland from the coastline reach the upper 70s. Dewpoints will climb into the mid to upper 60s which will feel unusually muggy for early January. The brunt of the forcing with the front will stay north of the area, so overall coverage or intensity of the precipitation should be limited. A broken line of showers will precede the front, but many areas could see no more than a trace of precipitation.
Cold advection and relatively deep mixing on Sunday will result in cooler temperatures and breezy conditions. Gusts on Lake Moultrie could approach 25 kt so a Lake Wind Advisory may be needed. Temps will further cool off Sunday night into Monday, but no hazardous weather is expected.
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.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
Cool high pressure will prevail through Wednesday, then a cold front may sweep through Wednesday night or Thursday, bringing scattered showers.
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.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
The 12z TAF period begins with widespread dense fog across the entire area, including KCHS, KJZI, and KSAV. Fog is expected to remain dense through about 14-15z before dissipating. However, IFR conditions should hang around through late morning at KCHS and KSAV, and potentially midday at KJZI. Improvement to VFR is expected for the afternoon at all 3 sites, though occasional fog and stratus could pass through KJZI as it moves onshore from the coastal waters. Conditions then remain favorable for another round of widespread fog and very low stratus again tonight, likely beginning in early to mid evening hours. This fog and stratus will likely begin across the nearshore coastal waters and then spread onshore within light southerly flow. Guidance suggests that the fog will be dense again, and a prolonged period of IFR conditions is expected for the latter portion of the 12z TAF period.
Extended Aviation Outlook: Brief flight restrictions possible Saturday night as a band of showers accompanies a cold front. Gusty winds expected Saturday and Sunday.
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.MARINE...
Today through tonight: Light southerly flow will prevail today with speeds mostly around 5-8 knots. Overnight, winds will remain southerly though the flow should start to increase as a cold front starts to draw a bit closer from the west. Wind speeds should pick up to around 10 knots and could be 10-15 knots at times. Seas should average 1-2 feet through the period.
Of greater forecast concern is fog across the local waters. Through sunrise, the expectation is that fog will continue to expand and become more dense. Then with no mechanism to scour it out during the day, fog of some flavor will likely stick around through most (all?) of the day. Then as we move into the evening hours, fog should start to expand and worsen again persist through early Saturday morning. A Dense Fog Advisory is in effect for all waters including Charleston Harbor, currently through the early afternoon. While there could be some improvement during the afternoon, advisory conditions should then occur again overnight and the current advisory will either need to be extended or a new one issued.
Marine fog could persist into Saturday or even Saturday night as warm and moist air continues to move in from the south. However, with increasing wind speeds, the fog may become thinner or less dense during this time. Drier air will move in behind a cold front late Saturday night, scouring out any residual fog.
Gusty WNW winds expected Sunday and Sunday night. Wind gusts at or above 25 kt are fairly likely for all marine zones during this time, so we anticipate the issuance of Small Craft Advisories.
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.CLIMATE...
Record High Temperatures: January 9: KCHS: 78/2012 KSAV: 77/2008
January 10: KCHS: 79/2008 KSAV: 81/1972
Record High Minimum Temperatures: January 10: KCHS: 60/1974 KCXM: 62/1974 KSAV: 63/1937
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Dense Fog Advisory until 10 AM EST this morning for GAZ087-088-
099>101-114>119-137>141.
SC...Dense Fog Advisory until 10 AM EST this morning for SCZ040-
042>045-047>052.
MARINE...Dense Fog Advisory until 1 PM EST this afternoon for AMZ330-
350-352-354-374.
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NEAR TERM...BSH SHORT TERM...JRL LONG TERM...JRL AVIATION...BSH/JRL MARINE...BSH/JRL