


Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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988 FXUS62 KCHS 180931 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 531 AM EDT Sat Oct 18 2025 .SYNOPSIS... High pressure will remain across the region through tonight. A cold front will move through Sunday night, followed by high pressure early next week. Another cold front will then arrive Tuesday night, with high pressure to follow. && .NEAR TERM /THROUGH TONIGHT/... Through Daybreak: 18/05z temperatures were running several degrees colder than the 18/01z NBM given the nearly ideal radiational conditions in place. This trend will continue through daybreak with low temperatures likely ending up quite a bit cooler than what the forecast depicts. National "Break the Glass" criteria is not met, so manual local adjustments to the gridded forecasts were not made despite observations and trends. Some areas of interior Southeast South Carolina up into the Francis Marion National Forest and interior upper Charleston County may very well see lows bottom out into the upper 40s with a few isolated instances of mid 40s. Today and Tonight: Deep-layered high pressure will maintain its influence on the region through tonight. The center of the surface high is forecast to shift offshore of the Southeast U.S. coast later this afternoon and tonight which will yield a weak southerly flow through the early morning hours Sunday. Some localized decoupling is likely to develop tonight and there will likely be some pockets of strong radiational cooling that occurs, especially in the typically more sheltered areas like the Francis Marion National Forest. Low-level thickness schemes support highs in the upper 70s/lower 80s inland with lower-mid 70s at the beaches where the flow will be more heavily influenced the the cooler Atlantic waters. Overnight lows will drop into the mid-upper 50s inland with upper 60s/near 70 at the beaches. A few lower 50s could occur where localized decoupling develops. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... A strong cold front will approach Sunday afternoon then cross the area Sunday night. A fairly contiguous line of showers is expected to be moving into our western zones shortly after daybreak. Forcing looks to diminish during the day, and there could be little precipitation associated with the frontal band by the time it reaches the coast late Sunday afternoon. The forecast also shows isolated thunderstorms across inland areas in the afternoon. Warm advection and pre-frontal compression should push high temps to around 80 degrees in most spots. Cool and dry weather then expected Monday and Monday night before another front approaches late Tuesday. Monday night lows should be solidly in the 40s away from the coast due to strong radiational cooling. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... Dry high pressure expected through the extended forecast with no appreciable weather. && .AVIATION /09Z SATURDAY THROUGH WEDNESDAY/... 18/12z TAF Discussion: KCHS/KJZI/KSAV: VFR through 19/12z. Extended Aviation Outlook: VFR conditions are expected at all terminals through Wednesday. However, gusty southerly winds (15-20 kt) are possible at all terminals Sunday in advance of a cold front. && .MARINE... Through Tonight: A southerly wind flow will strengthen today and especially tonight as high pressure shifts offshore and a cold front approaches from the west. Speeds will average less than 10 kt today, although there could be some localized enhancements near the land/sea breeze interface this afternoon, then increase to 10-15 kt tonight. Seas will range from 2-3 ft nearshore waters and 3-5 ft over the Georgia offshore waters. Sunday through Wednesday: Marginal Small Craft Advisory conditions, mainly due to 25 kt gusts, possible Sunday night into Monday morning following a strong cold front. Another brief surge will follow a secondary cold front Tuesday night, but winds/seas look to remain below advisory thresholds. Rip Currents: Another period of enhanced rip current risk is possible for all beaches Sunday due to increasing swell and gusty onshore flow ahead of an approaching cold front. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$