FXUS62 KCHS 120611 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 111 AM EST Fri Dec 12 2025
.SYNOPSIS...
High pressure will prevail through Saturday, then an arctic cold front will sweep through late Sunday. Dry high pressure will then rebuild into the region.
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.NEAR TERM /THROUGH TONIGHT/...
Today: Aloft, zonal flow will prevail across the forecast area within a broadly cyclonic flow regime. At the surface, high pressure will be situated south and southeast of the area with a boundary draped west to east across NC back through the lower MS Valley. Modest southwesterly flow across the area will help yield a pleasant day with mostly clear skies. Highs are forecast to peak around or just over 60 across southeast SC, and the low to mid 60s across southeast GA.
Tonight: Quiet conditions will continue. Expect mostly clear skies and likely just enough light southwesterly flow to prevent ideal radiational cooling conditions. We should still see some upper 30s inland ranging to low to mid 40s along the coast.
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.SHORT TERM /SATURDAY THROUGH MONDAY/...
...Bitter Cold Temperatures expected Sunday night...
The most impactful part of this period will be the bitter cold temperatures expected behind an arctic cold front Sunday.
However, for Saturday, conditions will be more pleasant before the arctic front, with zonal upper level flow and low level southwest winds. Expect highs on Saturday to warm to above normal in the mid 60s to near 70. These temperatures will be warmer than we have been so far this month of December by about 5 to 10 degrees! A mild night Saturday night as a deep upper trough takes shape over the Great Lakes and into the mid Atlantic. With southwest low level flow, lows will stay in the upper 40s inland to the lower to mid 50s closer to the coast.
By Sunday, the upper trough continues to sharpen and move eastward, which will help to drive an arctic front through the region. Models continue to have differences in timing with the front, but blended solutions point toward late morning to early afternoon for it to pass through the region. Only marginal moisture will be present with the front. So, other than some isolated showers, not expecting and significant precipitation ahead of the front. Temperatures will likely reach their highest through early afternoon, then begin to fall through the 50s behind the strong cold front through the reminder of the afternoon. A strong surface ridge will build from the northwest through Sunday night, producing brisk northwest to north winds, driving arctic temperatures southward through the region. Lows Sunday night likely ranging from the upper teens inland to the lower to mid 20s closer to the coast. A Cold Weather Advisory is looking likely for Sunday night. These type of cold temperatures will be very hazardous, and could cause issues with exposed pipes/plumbing.
Monday, the surface ridge moves over the region with lighter north- northeast winds. Even with sunny skies, highs expected to only reach 40 to 45, which would be at least 15 degrees below normal!
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.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
Monday night will start off very cold as the surface ridge sits over the region with light winds and clear/mostly clear skies. Lows around 20 to the lower 20s well inland, and mid to upper 20s closer to the coast. With lighter winds and slightly higher surface dewpoint temperatures possible, patchy to scattered frost cannot be ruled out.
Tuesday through Friday, models indicate a pattern change with generally zonal upper flow and temperatures moderating. High temperatures possibly back near normal by Wednesday, and even above normal Thursday and Friday with highs well into the 60s to near 70. There are model differences with precip. chances later in the week with the potential for some upper troughing and coastal trough. Blended solutions and current forecast keep slight chance PoPs for showers Thursday, but confidence is low at this time.
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.AVIATION /06Z FRIDAY THROUGH TUESDAY/...
VFR conditions will prevail at KCHS, KJZI, and KSAV through 06z Saturday.
Extended Aviation Outlook: Gusty winds are expected Sunday into Monday morning behind a strong arctic cold front. Otherwise, VFR conditions expected Saturday through early next week.
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.MARINE...
Today through tonight: Winds across the local waters will turn southwesterly and increase into the 10-15 knot range through the afternoon. This southwest flow regime with speeds around 10-15 knots should continue through the overnight as well. Seas are forecast to average 2 feet today, then 2-3 feet overnight.
No highlights expected through Saturday night with a ridge of high pressure centered east-southeast of the waters and southwest winds of 10 to 20 knots and seas generally 2 to 3 feet.
By Sunday, an arctic front is expected to push through the waters, likely passing east of the waters by late afternoon/early evening. Winds are expected to increase dramatically behind the front, with high end SCA conditions likely by late afternoon/early evening. There is a possibility for low end Gale coniditons, especially for AMZ350 and AMZ374. High end SCA to possibly low end Gale conditions are likely to persist into Monday night, especially for seas of 6 feet or greater beyond 20 nm offshore.
Tuesday, winds and seas are expected to fall back below any highlight levels as high pressure builds over the waters. Winds generally 15 knots or less and seas 2 to 4 feet, highest well offshore.
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.CLIMATE...
Record Low Temperatures:
December 15: KCHS: 15/1962 KCXM: 23/1943 KSAV: 19/1962
Record Low Maximum Temperatures:
December 15: KCHS: 39/1943 KCXM: 38/1904 KSAV: 38/1904
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None. SC...None. MARINE...None.
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NEAR TERM...BSH SHORT TERM...RFM LONG TERM...RFM AVIATION...BSH/RFM MARINE...BSH/RFM