FXUS62 KCHS 221834 AFDCHS
Area Forecast Discussion National Weather Service Charleston SC 234 PM EDT Sun Mar 22 2026
.WHAT HAS CHANGED...
Key Messages updated. The Aviation Section has been updated for the 18Z TAF issuance. A Gale Watch has been issued for all marine waters beginning Monday night through Tuesday night.
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.KEY MESSAGES...
- 1) A strong backdoor cold front will move through Monday
evening, resulting in breezy winds and cooler conditions Tuesday.
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.DISCUSSION...
KEY MESSAGE 1: A strong backdoor cold front will move through Monday evening, resulting in breezy winds and cooler conditions Tuesday.
A strong backdoor cold front will push through the region late Monday night, bringing breezy winds and noticeably cooler temperatures in its wake. Following highs in the mid to upper 80s on Monday, temperatures will fall into the 60s for Tuesday and Wednesday. Despite the noticeable cool-down, temperatures will align more closely with seasonal norms.
A line of showers and thunderstorms could develop ahead of the front, but coverage should remain limited, with rain chances at or below 25%. Models suggest storms could move in from the northwest during the evening. As they develop, instability could begin to weaken, with SBCAPE values peaking near 1200 J/kg before decreasing. Early on, this moderate instability combined with 35-45 kt of wind shear could support an isolated strong thunderstorm capable of producing damaging wind gusts, mainly across the Lowcountry. As the storms shift south toward Georgia later in the night, weakening instability could reduce their strength.
Outside of convection, breezy conditions are expected late Monday night into Tuesday. Most places are likely to see gusts up to 25 mph. The immediate coast will see the gustiest conditions with a 50-60% chance of wind gusts exceeding 30 mph.
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.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
Prevailing VFR through the 18Z TAF period. Gusty SW winds will diminish with nightfall. Winds will likely remain elevated overnight, generally around 8 knots or so, with gustiness returning Monday late morning.
Extended Aviation Outlook: A backdoor cold front will move through Monday evening, possibly producing a few showers/thunderstorms at the terminals. Northeasterly winds could gust up to 25 kt behind the front on Tuesday.
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.MARINE...
Rest of today into Monday: High pressure should generally support southwest winds between 10 to 15 kts with gusts around 20 kts. Wave heights should range between 3-4 ft.
Monday through Friday: Forecast guidance remains consistent regarding the timing and progression of a backdoor cold front moving across the marine zones late Monday. In the wake of the front, a 4-5 mb pressure gradient is expected to develop across the marine zones Monday night into Tuesday. Winds over the Atlantic waters will shift out of the northeast and rapidly increase late Monday night.
Gusts are likely to peak late Tuesday morning around 30 to 35 kt with potential for 35 to 40 kt. Gale Watches have been issued for all marine zones, including the Charleston Harbor. Wave heights are expected to peak Tuesday, reaching 6-9 ft within 20 nm and 9-11 ft across the Georgia offshore waters (from 20-60 nm).
By Wednesday, high pressure building into the region should lead to diminishing winds and gradually subsiding seas, although 6 ft waves could persist over the outer Georgia waters. Conditions are expected to continue improving into Thursday.
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.CLIMATE...
Record High Temperatures:
March 22: KCHS: 88/2011
March 23: KCHS: 87/1995
March 27: KCHS: 87/2021 KCXM: 81/2021 KSAV: 89/2021
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.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None. SC...None. MARINE...Gale Watch from Monday evening through Tuesday evening for
AMZ330. Gale Watch from Monday evening through Tuesday evening for AMZ350-352-354. Gale Watch from Monday evening through late Tuesday night for AMZ374.
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BRS/CPM