Area Forecast Discussion
Issued by NWS Charleston, SC

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611 FXUS62 KCHS 060146 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 946 PM EDT Wed Jun 5 2024 .SYNOPSIS... High pressure will extend across the area through tonight. A cold front will approach from the northwest on Thursday, then slowly move through on Friday. High pressure returns for the weekend, then another cold front will move through Monday. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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While we generally remain under the influence of Atlantic high pressure at the surface, a short wave aloft found near and north of the Savannah River will move through between now and 5 am. So despite the nocturnal environment, the forcing from this feature, plus PWat of 140-150% of normal, and lingering boundaries from previous convection, we hold onto isolated to scattered convection until the short passes offshore by 6 am. The highest coverage will be mainly across the South Carolina counties, where we show 30-50%. A southerly flow, elevated dew points, and partly to mostly cloudy skies will result in a mild night. Lows will only drop to the upper 60s and lower 70s inland, mid and upper 70s closer to the coast.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/... Thursday: A shortwave trough is poised to ripple through the southeastern states in the afternoon to evening hours. At the surface a cold front will be positioned well to the west of the forecast area. Ahead of the cold front moisture will pool into the region, with PWATs increasing to around 1.6 inches. A combination of the increased moisture and forcing from the shortwave and the approaching cold front should result in decent shower and thunderstorm coverage in the afternoon. PoPs are generally in the 40- 50% range across the region, decreasing from west to east in the overnight hours. High temperatures are forecast to reach into the low to mid 90s, with overnight lows in the low to mid 70s. Friday and Saturday: Broad troughing will prevail aloft on Friday and Saturday, while at the surface a cold front slowly pushes through by Friday night. High pressure will begin building in at the surface on Saturday. Not much in the way of precipitation is expected with the cold front, however it will likely bring a decrease in dew points. A slight chance of showers and thunderstorms is possible on Friday afternoon, mainly along the coastal counties associated with the passing cold front`s interactions with the local sea breeze. PWATs Saturday are forecast to drop below 1 inch on, with a dry forecast maintained. Temperatures each day are expected to reach into the low 90s, with overnight lows in the mid to upper 60s, with around 70 at the beaches. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... A return to a typical summertime pattern of afternoon showers and thunderstorms should return late in the weekend and into early next week. A cold front is expected to approach the forecast area early next week, with PWATs increasing to around 1.5 inches by mid week. Isolated to scattered showers and thunderstorms are possible each afternoon through mid week due to the increased moisture and interactions with the local sea breeze. Temperatures are expected to be right around normal to slightly above normal. && .AVIATION /02Z THURSDAY THROUGH MONDAY/... KCHS/KJZI: Since there is a short wave moving through overnight, we do show the potential for some convection. We include VCTS from 06-09Z as a result. Otherwise, it`ll remain VFR. The potential for SHRA/TSRA with the cold front late Thursday occurs too late in the 00Z TAF cycle, so no mention at this time. Both sites will become a little gusty ahead of the front Thursday afternoon, peaking at least near 20 kt. KSAV: In all likelihood what little convection there is upstream from the terminal, will stay away through the night. So VFR is forecast. Also, any SHRA/TSRA with a cold front late Thursday occurs too late to include this far in advance. There will also be some gusts Thursday afternoon, at least as high as 15-20 kt. Extended Aviation Outlook: VFR. && .MARINE...
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Tonight: The local waters will be positioned under the western side of the Bermuda High pressure system, and with just enough of a gradient in place, southerly winds will be as high as 10-15 kt. There will even be some gusts at times to near 20 kt through the night. Seas will average 2-3 feet. Mariners can expect at least isolated t-storms after midnight. Thursday through Sunday: SW winds on Thursday afternoon will shift to the NW by Friday afternoon as a cold front slowly pushes through the region. SW winds will resume by Sunday afternoon. Wind speeds on Thursday will be slightly elevated, with 15 to 20 knots across the marine zones. Thereafter, speeds should remain around 10 knots. Seas are expected to average 2 to 3 ft through the period.
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&& .TIDES/COASTAL FLOODING...
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Astronomical tides will remain elevated on Thursday. Although the wind direction along the coast isn`t ideal for driving large positive tidal departures, conditions should still be sufficient to produce departures in the 0.4 to 0.6 ft. Therefore, the high tide Thursday evening could peak right around 7.0 ft MLLW in Charleston. Coastal Flood Advisories could be needed for Charleston and coastal Colleton counties.
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&& .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM... SHORT TERM...CPM LONG TERM...CPM AVIATION... MARINE...