Area Forecast Discussion
Issued by NWS Charleston, SC

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739 FXUS62 KCHS 201510 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 1110 AM EDT Mon May 20 2024 .SYNOPSIS... High pressure will persist for most of this week. A series of upper level disturbances should impact our area next weekend. && .NEAR TERM /THROUGH TONIGHT/...
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Cool air advection (between building ridging inland and troughing well offshore) is the name of the game across the area as we move toward midday, with widespread strato-cu developing at the top of BL in the modified-maritime airmass. Strengthening upper subsidence will keep a dry forecast in place. Highs in the upper 70s to lower 80s anticipated...coolest along the coast and around Lake Moultrie. Tonight: Any diurnal cloud cover will fade quickly this evening with mainly clear skies anticipated thereafter. Along with diminishing winds and lower dewpoints, lows will dip into the upper 50s inland to the middle 60s along the coast.
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&& .SHORT TERM /TUESDAY THROUGH THURSDAY/... Tuesday: A positively tilted mid-level trough will be just off the Southeast U.S. coast in the morning. It will transition into a cut- off Low in the evening and overnight. Meanwhile, a ridge will strengthen over the Southeast U.S. during the day and at night. Broad High pressure centered to our north in the morning will shift off the Mid-Atlantic Coast as the day progresses. Though, it`s southern periphery will continue to be the dominant synoptic feature for our weather during the day and into the night. Subsidence will yield dry conditions with mostly sunny/clear skies. High temperatures should be in the mid 80s, except cooler at the beaches. Lows should range from the upper 50s far inland to the mid 60s closer to the coast. Wednesday: The mid-levels will consist of a cut-off Low meandering off the Southeast coast, while a ridge prevails over the Southeast U.S. At the surface, High pressure along the Southeast coast in the morning will shift offshore into the afternoon. A front will slowly approach from the north and northwest during the evening and overnight. Though, it won`t make it near our area as the periphery of the High remains the dominant synoptic feature. Ongoing low and mid-level subsidence will continue to bring our area dry conditions with mostly sunny/clear skies. Expect an inland moving sea breeze during the afternoon. Highs will peak in the upper 80s, except cooler at the beaches. Lows should range from the lower 60s far inland to the lower 70s along the immediate coast. Thursday: A mid-level ridge over the Southeast U.S. in the morning will weaken as the day progresses. Surface High pressure just off the Southeast coast in the morning will move further offshore as the day progresses. The front to our north and northwest will continue to approach. However, it won`t make it to our area. This periphery of the High will bring yet another day with dry conditions. Expect fair weather cumulus in the afternoon along with a sea breeze. High temperatures should be in the upper 80s to lower 90s, except cooler at the beaches. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... Expect west southwest mid-level flow over our region Thursday night. A weak trough may pass to our north Friday night into Saturday, possibly followed by weak ridging on Sunday. Surface High pressure in the western Atlantic Thursday night will shift further offshore into the weekend. A cold front could approach from the north and northwest later Friday, then lift north on Saturday. Expect some diurnal convection on Friday, with convection more likely during the weekend. High temperatures will be a few degrees above normal each day. && .AVIATION /15Z MONDAY THROUGH FRIDAY/...
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KCHS/KJZI/KSAV: Scattered MVFR ceilings have emerged this morning with strato-cu across much of the area at the top of the cooler boundary later. While improved mixing this afternoon is likely to scatter clouds somewhat, there is potential for at least occasional MVFR cigs at CHS, JZI, and SAV through early afternoon, represented with TEMPO groups in the updated TAFs. VFR conditions prevail again by mid-afternoon with mainly SCT cu based around 3-4 kft persisting. Gusty NE winds developing late morning will continue through the afternoon, with 15-20 kt gusts expected. Turning clear this evening with diminishing winds. Extended Aviation Outlook: VFR.
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&& .MARINE... Surface high pressure will be building along the Atlantic coast through today. The resulting tighter pressure gradient across the coastal waters will continue to produce gustier northeasterly winds today and tonight. Gusts of 20 to 25 knots will be common today with seas building to 3 to 5 feet in the nearshore waters and 4 to 6 feet in the outer Georgia waters. We have hoisted a Small Craft Advisory for the outer Georgia waters for today through early evening. It`s a bit more marginal across the nearshore waters with no headline planned at this time. But we will continue to monitor conditions for possible expansion of the SCA as we go through the day. Extended Marine: NE winds on Tuesday will shift around to the SE by later Wednesday as High pressure gradually shifts off our coast. This will lead to a more typical summer wind pattern beginning on Thursday. That`s when mariners should expect backing winds during the day, along with stronger wind gusts along the land/sea interface with the formation of the afternoon breeze. At night, winds should veer as low level jetting sets up along the coast. && .TIDES/COASTAL FLOODING...
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A Coastal Flood Advisory has been issued for the Charleston and Colleton County coastlines around this time of this evening`s high tide (7 PM). The combination of rising astronomical tides with the upcoming Full Moon and moderate NE winds will cause tides to be elevated through the middle of this week. Minor flooding is possible with the evening high tides again Tuesday and Wednesday along the South Carolina coast.
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&& .CHS WATCHES/WARNINGS/ADVISORIES...
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GA...None. SC...Coastal Flood Advisory from 6 PM to 8 PM EDT this evening for SCZ049-050. MARINE...Small Craft Advisory until 6 PM EDT this evening for AMZ350. Small Craft Advisory until 9 PM EDT this evening for AMZ374.
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&& $$ NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE...