Area Forecast Discussion
Issued by NWS Charleston, SC

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949 FXUS62 KCHS 041749 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 149 PM EDT Tue Jun 4 2024 .SYNOPSIS... High pressure will extend across the area through Wednesday. A cold front will approach from the northwest on Thursday, then slowly move through on Friday. High pressure returns for the weekend. && .NEAR TERM /THROUGH TONIGHT/...
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This afternoon: Radar finally showing some isolated showers developing well inland, over extreme northern Allendale county. The seabreeze is also developing, but no sign of any convection yet along it. It seems it needs to push a little further inland to potentially interact with other low level boundaries before possibly developing isolated showers/thunderstorms. Low level southerly winds still pretty light inland, but starting to pick up from the south-southeast along the coast with the seabreeze. Winds at the coast/beaches expected to be 10-15 mph with some higher gusts, and 5-10 mph elsewhere. High temperatures still expected to flirt with 90 inland, and mid to upper 80s closer to the coast. There is a weak upper level vort moving across the west/northwest portion of the are later this afternoon, and combined with modest mix-layered CAPE values of 1,000-1,500 J/kg, there is a small chance for an isolated strong storm with gusty winds to develop. Best chances for any isolated to scattered storms will be inland as the seabreeze pushes west and possibly collides with other low level boundaries. Tonight: Early evening convection should mostly favor inland areas and steadily dissipate through the late evening hours. The rest of the overnight is then expected to be dry. Lows are forecast to be in the upper 60s inland and the low 70s along the coast. Though there aren`t any significant fog concerns, some guidance would suggest potential for shallow ground fog across the far interior late in the period.
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&& .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... A relatively active pattern is anticipated during the period. A weak upper trough will persist with a series of shortwaves rippling through. Fairly deep southerly flow will maintain a moist airmass Wednesday and Thursday with PWATs around 1.85". A sea breeze each afternoon will provide an additional focus for convective development. The greatest convective coverage is expected to be inland. Friday, a cold front sags into the area, with deep westerly flow developing during the day. Compression ahead of the front is expected to produce a warm day with highs in the low to mid 90s. Drier air will move in during the morning. This, combined with mid-level subsidence, should limit convective coverage. However, given the cold front, we kept 20-30% PoPs, highest farther to the south where better moisture will exist. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... Although temps will remain fairly warm this weekend, the airmass will noticeably change due to substantially lower dewpoints. This should also limit the potential for convection. An increase in moisture early next week and some shortwave energy will bring a return to scattered diurnal convection. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/...
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Rest of today and tonight: VFR conditions are expected to prevail at KCHS, KJZI, and KSAV. The best chance for an isolated afternoon shower/thunderstorm is expected to be around KSAV, but changes are less than 20%. Wednesday: Increasing chances for afternoon showers/thunderstorms. Given 20-30% chances for convection start at the end of the current TAF period (18z Wed), have decided to leave mention out for now. Extended Aviation Outlook: Outside of any convection, conditions will be VFR through the period.
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&& .MARINE...
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This afternoon: No significant changes were made to the previous forecast. Generally southeast winds of 5 to 15 knots, strongest near the coast with the seabreeze. There could be some gusts of 15 to 20 knots near the coast later this afternoon. Seas expected to average 2-3 feet. Tonight: Continued relatively quiet with southeast winds of 5 to 10 knots. Could see isolated late night showers/thunderstorms, especially beyond 20 nm offshore. Wednesday through Sunday: High pressure will remain over the western Atlantic Wednesday through Thursday night, maintaining southerly flow at or below 15 kt, seas at or below 4 ft, and a daily sea breeze circulation along the coast. A cold front will move through on Friday, with winds turning W over the weekend.
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&& .TIDES/COASTAL FLOODING... Astronomical tides are on the rise this week. Although wind direction is not particularly favorable for surge, we continue to see a positive tidal anomaly of 0.5 to 0.7 ft. The evening high tides today through Thursday could reach at least 7.0 ft MLLW in Charleston, necessitating Coastal Flood Advisories. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...BSH/RFM SHORT TERM...JRL LONG TERM...JRL AVIATION...BSH/JRL/RFM MARINE...BSH/JRL/RFM