FXUS62 KCHS 092321 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 721 PM EDT Mon Mar 9 2026
.WHAT HAS CHANGED...
The Aviation section was updated for the 00z TAFs.
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.KEY MESSAGES...
- 1) Low clouds and fog are possible tonight, especially east of
I-95 and along the coast.
- 2) Unseasonably warm temperatures continue through Wednesday.
- 3) Showers and thunderstorms likely Thursday as a cold front
moves through.
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.DISCUSSION...
KEY MESSAGE 1: Low clouds and fog are possible tonight, especially east of I-95 and along the coast.
The forecast area continues to sit within this very summer-like pattern driven by subtropical high pressure out over the Atlantic. The airmass remains quite warm and relatively moist, and the nearshore coastal waters remain cool with water temperatures having steadily risen into the low 60s. We have also been in a routine of nocturnal fog and stratus development. This should continue to some degree again overnight, though guidance suggests it will remain closely aligned with the coolest shelf waters. Current thinking is that fog and low stratus will develop in the early morning hours, but low-level winds will take on a more southwesterly component which will prevent much from bleeding onshore. The immediate coast and the beaches have the best chance of seeing fog and stratus, mainly closer to sunrise. The overall risk for dense fog seems to be less than the last few nights as a result.
KEY MESSAGE 2: Unseasonably warm temperatures continue through Wednesday.
A broad ridge of high pressure will remain in place across the southeastern United States through Wednesday, allowing unseasonably warm conditions to persist. Afternoon highs will generally reach the 80s, while coastal areas remain slightly cooler, with temperatures in the upper 70s. Overnight temperatures will stay mild, with lows mainly in the lower 60s. Wednesday is expected to be the warmest day with highs in the middle/upper 80s and locations across interior Southeast Georgia could hit 90 degrees. Forecast temperatures could approach record highs and/or record high mins, especially on Wednesday (see Climate section below).
Isolated to scattered showers/thunderstorms are possible Tuesday afternoon, especially across the Tri-County area. However, with limited moisture and relatively low coverage, significant rainfall is not expected. No severe weather expected.
KEY MESSAGE 3: Showers and thunderstorms likely Thursday as a cold front moves through.
Upper level flow will shift on Thursday as a trough and surface cold front move east from the Tennessee River Valley toward the Atlantic. South to southwest flow ahead of the front will support increasing moisture across the region. Combined with unseasonably warm temperatures, this should provide enough instability for numerous showers and thunderstorms to develop ahead of the advancing front. Models show a line/broken line of convection pushing across the area in the late morning/afternoon period. The current time of arrival for the front passage (progged for Thursday evening) should keep instability somewhat limited, with SBCAPE values likely remaining below 1000 J/kg. With decent shear in the mix (60-70 kt), isolated strong thunderstorms appear possible at this time. If the front slows and delays rainfall into the evening hours, slightly greater instability could develop, increasing the potential for strong to marginally severe storms. Rainfall amounts of around one-half to one inch are expected. Flooding is not anticipated, especially as rainfall will be moving through relatively quick, though minor drainage issues could occur in urban or low-lying areas.
Temperatures will drop noticeably behind the front as cold air advection develops Thursday afternoon, with the most significant cooling occurring Thursday night. Lows will fall into the upper 30s across interior southeast South Carolina and into the 40s elsewhere away from the beaches. A much cooler day is expected Friday, with highs in the upper 60s to lower 70s. Temperatures then rebound into the 70s and 80s over the weekend.
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.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
The 00z TAF period begins with VFR conditions at KCHS, KJZI, and KSAV. Overall, there is a much lower chance for fog and stratus impacts at the terminals as current thinking is that it will remain offshore across the coastal waters. Therefore, we have kept the forecast VFR at KCHS and KSAV as both sites should be inland of the coast enough to lower the threat substantially. KJZI could be a bit tricky with its close proximity to the coast. We still advertise a period of IFR conditions in a TEMPO group from 09-12z. Any fog and stratus that does push inland should lift quickly and the rest of the day is expected to be VFR. There is some potential for isolated showers and thunderstorms late Tuesday afternoon, but chances of direct impacts this far out are too low to include in the TAF's (primarily KCHS and KJZI).
Extended Aviation Outlook: Flight restrictions due to low stratus/fog remain possible through mid-week. Brief flight restrictions may occur Tuesday in response to scattered showers and thunderstorms. Otherwise, look for a cold front to bring additional flight restrictions and breezy winds on Thursday.
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.MARINE...
Tonight: A stationary front will be to our north while High pressure is to our east. This synoptic flow will generate S to SSW winds 5-10 kt. This wind direction should usher deeper moisture over the cooler shelf waters, making it more likely for sea fog to form. The coverage and timing remains questionable, but the tendency is if/when it develops, it should stick around until just after daybreak Tuesday. Seas will average 2-3 ft within 20 nm and 3-4 ft for the GA waters beyond 20 nm.
Tuesday through Saturday: High pressure will be the dominant weather feature across the local waters through the middle of this week. This will result in S/SW winds 5 to 10 kt and seas 2 to 4 ft. A cold front will approach from the west late Wednesday, causing winds and seas to increase. At the least, Small Craft Advisories will be likely for most marine zones where we anticipate gusts to reach 25- 30 kt and seas 4-7 ft as early as Wednesday night. The cold front should cross through our waters Thursday, causing winds to veer out of the northeast in its wake. Gusts to gale force are possible across portions of our waters Thursday night and a brief Gale Watch/Warning could be needed. High pressure building into the region will lead to improving conditions into the weekend.
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.CLIMATE...
Record High Temperatures:
March 11: KCHS: 85/2015 KSAV: 87/2015
Record High Minimum Temperatures:
March 10: KSAV: 63/1909
March 11: KCHS: 63/2015 KCXM: 64/2016 KSAV: 64/1974
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.EQUIPMENT...
The KCLX radar is scheduled for radome panel replacement March 14-16, 2026. The radar will be down during this time. Users are encouraged to use data from the following nearby radar sites during the maintenance outage:
KCAE - Columbia, SC KLTX - Wilmington, NC KJAX - Jacksonville, FL KVAX - Moody AFB, GA KJGX - Robbins AFB, GA
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None. SC...None. MARINE...None.
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BSH