Area Forecast Discussion
Issued by NWS Charleston, SC

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883 FXUS62 KCHS 240549 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 149 AM EDT Mon Jun 24 2024 .SYNOPSIS... High pressure will remain over the western Atlantic through much of next week. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Tonight: Aloft, the local area will remain nestled between weak low pressure meandering over the western Atlantic off the Southeast Coast and a ridge extending west across the Deep South and into parts of the Southeast United States. At the sfc, weak low pressure will continue to track north and further away from the area tonight, pulling deeper moisture out of the local area. The pattern should support fairly quiet conditions with light winds away from the beaches and some lingering clouds in place. Sfc winds could even decouple for a few hours inland, but southwest winds should return and gradually increase late night as a trough approaches from the west-northwest heading through daybreak. Closer to the coast, the pressure gradient remains enhanced, so southwest winds should remain rather breezy during the night, gusting upwards to 15-25 mph at times (highest along Charleston County beaches). Temps will also remain mild ahead of the approaching trough overnight, generally only dipping into the mid 70s inland to upper 70s/around 80 near the beaches. && .SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY/... A broad upper ridge will remain over the central United States on Monday while a weak shortwave drops through southeast GA/SC in the afternoon. A weak surface front is forecast to drop into the area Monday afternoon, potentially providing a focus for afternoon convection. Fairly unidirectional W flow will result in a downslope trajectory, not only pushing temps into the upper 90s but potentially producing subsidence that works against convective initiation. The offshore winds will also keep the sea breeze pinned near the coast much of the day, with only a small amount of inland movement late in the afternoon. 0-6 km bulk shear expected to be 25-30 kt with SBCAPE around 1,000 J/kg. Given the approaching cold front, there could be some storm organization along and ahead of the front in the afternoon, though the downslope flow could limit the overall coverage. Heat indices are forecast to top out 105-108F in the afternoon, just shy of Heat Advisory criteria. The weak upper ridge pattern will transition to a weak trough over the Southeast Tuesday into Wednesday. At the surface, a weak surface wave will linger near the area Tuesday, then dissipate Tuesday night. A relatively typical summertime pattern is expected both days, with scattered mainly diurnal convection and highs in the 90s. Forecast heat indices both days top out just below 108F in a few spots. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... A potent shortwave will move through Thursday and Thursday night. On Friday, surface high pressure will be centered over the Northeast, with a deep onshore flow over the local area. Fairly good coverage of showers and thunderstorms expected Thursday and Friday. A deep layered ridge will build over the area for the weekend, decreasing diurnal convection coverage. && .AVIATION /06Z MONDAY THROUGH FRIDAY/...
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VFR conditions will prevail at CHS/JZI/SAV terminals through 06Z Tuesday. However, tempo MVFR cigs/vsbys can not be ruled out Monday afternoon through Monday evening as a trough pushes through the region with showers and/or thunderstorms that potentially impact the terminals. Confidence in timing/duration of the event remains too low to include in the latest TAF issuance, but flight restrictions could need to be included in later TAF issuances. Extended Aviation Outlook: Mostly VFR. However, convection will bring brief flight restrictions, mainly each afternoon and evening.
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&& .MARINE... Tonight: Weak low pressure will track north and further away from local waters overnight. The pressure gradient will remain enhanced in wake of this feature between sfc high pressure centered further offshore across the western Atlantic and a sfc trough approaching the Southeast United States late. As a result, southwest winds ranging between 15-20 kt with gusts around 25 kt are likely across nearshore SC waters off the Charleston County Coast and across offshore GA waters. Seas should also build to 4-6 ft in these waters overnight. Small Craft Advisories will therefore be in effect for these waters through the night. Elsewhere, seas should build up to 3-5 ft, falling just short of Small Craft Advisory levels. Extended Marine: A slight gradient enhancement will persist Monday and Monday night due to the cold front approaching from the west and high pressure offshore. Wind gusts and seas should remain just below Small Craft Advisory criteria. Monday night through Friday, a typical summertime maritime pattern expected with S or SW winds less than 15 kt and seas no greater than 4 ft. && .CHS WATCHES/WARNINGS/ADVISORIES...
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GA...None. SC...None. MARINE...Small Craft Advisory until 8 AM EDT this morning for AMZ350- 374.
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&& $$ NEAR TERM...DPB SHORT TERM...JRL LONG TERM...JRL AVIATION...Adam/JRL MARINE...DPB/JRL