FXUS62 KCHS 050734 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 234 AM EST Fri Dec 5 2025
.SYNOPSIS...
A frontal system will maintain unsettled weather through early next week, then cold high pressure will build in.
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.NEAR TERM /THROUGH TONIGHT/...
Satellite water vapor showed a thick band of deep moisture extending from the forecast area southwest to a closed low off the coast of Baja. The stream of moisture should continue through the day, PWs increasing to 1.6 to 1.8 inches by this afternoon. The H5 heights will remain oriented from SW to NE across the region, with a series of vort maxes tracking across the CWA through the near term period. At the sfc, a 1025 mb high centered over the coast of New England will likely surge SW over the forecast area today, reinforced by persistent rainfall falling across the Southeast U.S. High resolution guidance indicates that the wedge front will slip off the SC/GA coast by daybreak this morning. A frontal wave may form over the front this morning, tracking NE along the wedge front and slowly deepen off the coast of SC. As the low develops and departs, a thick band of 925-850mb frontogenesis should form across SE GA/SC late this morning, pushing east across the CWA through this afternoon. Rainfall totals during the daylight hours are forecast to range between .5-.75 inches. Given steady north winds, thick clouds, and rounds of moderate rainfall, temperatures should remain generally steady in the low to mid 50s.
Tonight, the associated cold front will push east off the coast during the overnight hours. West-southwest flow aloft will maintain deep moisture across the region. Slow height falls and rounds of upper divergence should support a broad area of light rainfall tonight. Overnight rainfall may remain a 0.25" or less across the forecast area. Low temperatures are forecast to range in the 40s, with the coolest readings in the low 40s surrounding Lake Moultrie.
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.SHORT TERM /SATURDAY THROUGH MONDAY/...
The Southeast will remain on the eastern periphery of a broad longwave upper trough Saturday through Monday. At the surface, a quasi-stationary frontal boundary will remain near the SC/GA coast. A series of shortwaves embedded in the mean flow will lift northeast through the area during the period, bringing periods of light to moderate rain. At this point it seems that the best chances for rain will be during the daytime periods. Most areas should see widespread light to moderate rain Saturday, tapering off Saturday evening. Then another batch of rain moves in from the southwest late Sunday morning, continuing through the afternoon. A final round of showers will move through on Monday as the main upper shortwave lifts northeast. High pressure well north of the area will maintain weak cold advection. This, in concert with overcast skies through the period, will keep high temperatures generally in the 50s and lows in the 40s. The rainfall will not be particularly heavy (3-day totals generally less than 0.75"), which should minimize flooding concerns.
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.LONG TERM /MONDAY NIGHT THROUGH THURSDAY/...
Cool, dry high pressure will build in from the west Monday night. Overnight lows will dip below freezing in many areas away from the coast Monday night and Tuesday night. Daytime highs should push back into the 60s for most areas by Wednesday.
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.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
6Z TAFs: The leading edge of cold air damming will spread across the terminals around daybreak. North winds should generally remain, speeds between 5 to 10 kts through the TAF period. Deep forcing and moisture should yield widespread moderate rainfall across the region through much of the day. Forecast soundings indicate that cloud basses will gradually lowers through the day, reaching IFR to LIFR by late this morning. Lingering CAD tonight may yield some stratus build down, however, ongoing rainfall may keep the BL mixed enough to limit and fog formation. Each TAF will highlight the potential for ceilings falling below 500 ft.
Extended Aviation Outlook: A relatively prolonged period of ceiling restrictions expected Saturday through Monday. Prevailing MVFR with periods of IFR are expected. Periods of rain could occasionally reduce visibilities as well. Improving conditions later Monday or Monday night.
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.MARINE...
Today and tonight: An area of low pressure is expected to develop over the marine zones this morning, tracking off to the northeast this afternoon. Light winds will vary directions this morning as the low develops. As the low departs, winds should shift from the NNW with speeds increasing to around 10 kts. A band of moderate showers with isolated embedded thunderstorms should push across the waters late this afternoon and evening. Rainfall rates within the rain band may limit visibility to 2 SM or less at times. Wave heights are forecast to range between 2-4 ft today, decreasing to 2-3 ft tonight.
A brief period of marginal Small Craft Advisory conditions possible for the Charleston nearshore and GA offshore waters Monday afternoon into Monday night. Another round of marginal advisory conditions possible Wednesday night and Thursday.
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.TIDES/COASTAL FLOODING...
A Coastal Flood Advisory has been posted for Charleston and coastal Colleton counties until 9 AM this morning. Observation trends and recent guidance indicates that tide levels should peak between 7.2-7.4 ft MLLW. High tide should occur around 7:43 AM.
Further south, from Beaufort County through the southeast Georgia coast, high tide should peak below flood stage around 9.3 ft MLLW.
Astronomical tides will remain elevated through the weekend. Coastal Flood Advisories could be needed for morning high tide cycles, primarily at Charleston Harbor (Charleston and Coastal Colleton counties) through Sunday morning.
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None. SC...Coastal Flood Advisory from 6 AM to 9 AM EST this morning for
SCZ049-050.
MARINE...None.
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NEAR TERM...NED SHORT TERM...JRL LONG TERM...JRL AVIATION...JRL/NED MARINE...JRL/NED