FXUS62 KCHS 211151 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 651 AM EST Sun Dec 21 2025
.SYNOPSIS...
High pressure continues to prevail today, with a cold front then expected to dive across the region tonight into Monday. High pressure then returns Tuesday, resulting in above normal temperatures and dry conditions for the remainder of the holiday week.
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.NEAR TERM /THROUGH TONIGHT/...
The mid-levels will consist of a trough passing well to our north today, with somewhat zonal flow over our area. The trough amplifies as it moves offshore tonight, causing flow to turn to the NW overhead. At the surface, High pressure will prevail this morning, then shift away into the afternoon. Mostly sunny skies will yield above normal temperatures, generally in the 60s, to near 70 degrees across the Altamaha River and vicinity. A dry cold front will move southward through our SC counties late this afternoon or early evening, then through our GA counties this evening, causing a brief increase in clouds and a wind shift. As this front moves south of our area overnight, strong High pressure will build to our north. The combination of mostly clear skies and cold air advection tonight will cause temperatures to drop into the 30s far inland, and 40s at/near the beaches.
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.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
Breezy northeasterly winds will persist across the region Monday in the wake of FROPA, with gusts up to 20 kts possible through the afternoon in areas near/along the coast. Given the influx of CAA, will see highs be a touch cooler than Sunday, as temperatures only warm into the lower 60s.
Sfc high pressure then slides across the region again Tuesday, allowing highs to rebound back into the upper 60s to lower 70s with the aid of southwesterly flow and partly sunny skies. Warming trend continues into Wednesday as upper level ridging amplifies across the central CONUS. As such, expect afternoon highs in the low to mid 70s to prevail Christmas Eve.
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.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
Upper level ridging continues to dominate into the extended, with its placement sliding a bit more eastward over the the Ohio River Valley by Thursday. Thus, have above normal temperatures (low to mid 70s) and dry conditions continuing through the holidays.
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.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
12Z TAFs: Satellite indicates low stratus across much of our area. Surface observations indicate IFR at many locations, especially across Southeast GA. We added an IFR TEMPO group for KCHS and KJZI, and maintained the IFR TEMPO group for KSAV. Conditions will improve at roughly 13-14Z, with VFR then prevailing. A dry cold front will move through during the late afternoon and evening, causing a wind shift.
Extended Aviation Outlook: A period of MVFR cigs will be possible Monday morning in the wake of FROPA, with northwesterly gusts up to 20 kts. Otherwise, expect VFR conditions to prevail.
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.MARINE...
Today and Tonight: High pressure will prevail this morning. A dry cold front will move southward through our SC waters late this afternoon or early evening, then through our GA waters this evening, with winds turning to the NE behind the front. Strong High pressure will build to our north overnight. The combination of the surface pressure gradient enhancing and cold air advection will cause winds to increase and become gusty this evening and overnight. We have Small Craft Advisories up for all of the ocean waters due to winds and seas. It's borderline whether we'll need a Small Craft Advisory for the Charleston Harbor tonight.
Monday through Tuesday: Breezy northwesterly winds look to persist for much of Monday morning, before gradually tapering off into the afternoon. Nonetheless, will still see seas range between 5-7 ft during this time - keeping SCAs in effect through at least Monday evening. Should then see the inner SC/GA waters drop off overnight, with some indications that the outer Georgia waters may hang onto advisory level conditions until late Tuesday afternoon or evening. Will continue to monitor trends in the meantime.
Wednesday Onward: No high confidence marine concerns at this time.
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Dense Fog Advisory until 9 AM EST this morning for GAZ100-101-
114>119-137>141.
SC...Dense Fog Advisory until 9 AM EST this morning for SCZ047-048-
051.
MARINE...Small Craft Advisory from 9 PM this evening to midnight EST
Monday night for AMZ350. Small Craft Advisory from midnight tonight to midnight EST Monday night for AMZ352-354. Small Craft Advisory from 9 PM this evening to 6 PM EST Tuesday for AMZ374.
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NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE...