FXUS62 KCHS 230148 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 848 PM EST Mon Dec 22 2025
.SYNOPSIS...
High pressure will prevail through the holiday week.
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.NEAR TERM /UNTIL 6 AM TUESDAY MORNING/...
A wedge of high pressure will maintain its influence on the region tonight. Winds at buoy 41008 have been showing signs of backing with time suggesting the genesis of a weak coastal trough is ongoing. Indeed, weak isentropic ascent rooted along the 290-300K surfaces is aiding in the production of a 5000 ft ceiling along parts of the Georgia coast which has been slowly growing in size since sunset. These clouds are expected to steadily expand inland and to the north through the night as the coastal trough sharpens offshore. While no rainfall is expected over land, the thickening cloud cover will likely have a warming influence on overnight temperatures, especially along the Georgia and far southern South Carolina coast. Temperatures in these areas may only fall another few degrees before leveling out and possibly even rising slightly during the early morning hours. Farther inland, the boundary layer is quickly decoupling with mainly clear skies. This is promoting strong radiational cooling conditions with some spots over the Francis Marion National Forest already reporting temperatures in the upper 30s/lower 40s as of 23/0130z. Pinning down lows will be a challenge as radiational processes will weaken with time as clouds thicken from the south. Updated low favor upper 30s/lower 40s across northern parts of Dorchester, Berkeley and upper interior Charleston County (some mid 30s in the spots over the Francis Marion National Forest) with mid-upper 40s elsewhere except lower-mid 50s at the beaches.
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.SHORT TERM /6 AM TUESDAY MORNING THROUGH THURSDAY/...
Tuesday through Christmas: Short term guidance indicates that a strong H5 ridge will remain centered over the Gulf, with the ridge axis extending across the central CONUS. During the period, an amplified wave will ripple across New England, pushing over the north Atlantic on Christmas Eve. This pattern will keep the forecast area under dry NW flow aloft. At the sfc, high pressure should remain centered over the northern Gulf coast, with a possible dry cold front late Christmas. Overall, the forecast will feature dry and very mild conditions through the short term period. Temperature should trend warmer through Christmas, with Christmas temperatures featuring lows around 50 and highs in the mid to upper 70s.
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.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Very mild and dry weather will continue across the forecast area through this weekend. The H5 pattern will continue to feature a shallow longwave ridge across the southern CONUS. High pressure will remain across the Southeast U.S. through Saturday night. By Sunday, a cold front will approach from the west, return flow will keep temperatures in the mid to upper 70s. The cold front is timed to pass over the region Sunday evening and night. Isolated rain showers gusty NW winds should accompany the passage of the front. Temperatures may cool by 15 degrees by Monday, with highs near 60 degrees.
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.AVIATION /01Z TUESDAY THROUGH SATURDAY/...
23/00z TAF Discussion: KCHS/KJZI/KSAV: VFR through 24/00z.
Extended Aviation Outlook: A brief period of MVFR cigs/vsbys will be possible Wednesday morning due to fog or stratus development. Otherwise, expect VFR conditions to prevail.
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.MARINE...
Tonight: Winds are finally showing some signs of diminishing, but still remain solidly northeast. Speeds near 20 kt with gusts to 25 kt will persist for a few more hours. Seas remain above 6 ft as well per buoy observations, but both winds and seas should drop below advisory thresholds across the nearshore waters by midnight or 1 AM. Seas will remain above 6 ft over the Georgia offshore waters through the night.
Tuesday: Small Craft Advisory will continue across the offshore Georgia waters through Tuesday afternoon due to lingering 6 ft seas. Marine conditions then improve Tuesday evening, with southwesterly winds around 10 kts and seas dropping to 4 ft.
Wednesday Through Saturday: High confidence in no marine headlines. The pattern will support winds around 10 kts and seas between 2 to 4 ft.
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None. SC...None. MARINE...Small Craft Advisory until 1 AM EST Tuesday for AMZ350-352-354.
Small Craft Advisory until 6 PM EST Tuesday for AMZ374.
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NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE...