Area Forecast Discussion
Issued by NWS Charleston, SC

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000 FXUS62 KCHS 151703 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 103 PM EDT Mon Aug 15 2022 .SYNOPSIS... A cold front will move into the region tonight and Tuesday, lingering in the vicinity through late week. && .NEAR TERM /THROUGH TONIGHT/...
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A broad mid level trough will encompass much of the eastern U.S. today. Shortwave energy dropping out of northwest flow will move into the mid-Atlantic states and Carolinas later in the day. This will help send a weak area of low pressure and associated front towards the area. The daytime hours should largely remain dry with the better forcing staying outside of the area. High temperatures are forecast to reach the low to perhaps mid 90s across most locations inland of the beaches. No major changes were needed with the early afternoon update. Tonight: Both the cold front and wave of low pressure draw closer to the area, while stronger vertical wind fields and better forcing also move in. But on the flip side, the overall thermodynamic environment is rather unimpressive. Latest indications are for a band of showers and t-storms to move in during the middle of the evening, but to steadily weaken as it shifts east and southeast per various simulated satellite products and model consensus. Provided that cold- pooling doesn`t occur, there would be no risk for severe weather. But with a weak surface low in the vicinity and 0-6 km Bulk Shear around 30 kt, the potential is non-zero. Plus it is northwest flow, which often can cause stronger activity than previously anticipated. We shall see. For now we have scattered coverage through the night, with the highest probabilities of 40-50% north and northwest. Since there will be greater moisture content, it won`t be as cool as the past two nights. In all likelihood, min temps won`t get down below 70F.
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&& .SHORT TERM /TUESDAY THROUGH THURSDAY/... A stalled front will linger through the period as shortwave energy propagates across the region. With decent forcing in place, showers and thunderstorms can be expected each afternoon/evening. Tuesday and Wednesday: The aforementioned front will progressively shift through the region on Tuesday before shifting offshore late and then linger in the vicinity on Wednesday. PWATs will generally be between 1.5-2.0 inches so sufficient moisture will be in place to support at least scattered showers each day. As typical for summertime, thunder will be possible within any showers that do form. Otherwise, high temperatures will be in the mid 80s to mid 90s on Tuesday with slightly cooler temperatures on Wednesday. Lows will be in the upper 60s to mid 70s. Thursday: While the forecast will likely need to be refined, Thursday looks to be the most active day in the period. There are hints of a weak low forming along the front which will give way to better forcing and increased moisture. In contrast to previous days, PWATs will be greater than 2.25 inches. Therefore, heavier bouts of rainfall will be possible which could lead to minor flooding, especially in low-lying areas and/or areas that received decent rainfall in the previous days. At this time, our forecast highlights QPF ranging from 0.75 inches to ~2.0 inches. High temperatures will be in the low 80s to low 90s. && .LONG TERM /THURSDAY NIGHT THROUGH MONDAY/... A stalled front will linger near or across the area through early next week as a mid-level trough edges closer. This pattern will keep the weather quite active. With PWATs greater than 2.0 inches and sufficient forcing, scattered to numerous showers and thunderstorms will be possible each day. The main threat through the period will be heavy rainfall and minor flooding, with the severe threat being low. Otherwise, high temperatures will mostly be in the 80s with a few areas hitting low 90s. Lows will be in the upper 60s to mid 70s. && .AVIATION /18Z MONDAY THROUGH SATURDAY/...
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Prevailing VFR through 18z Tuesday. The probability for direct impacts with any shower or thunderstorm late this evening and overnight is too low to include explicit mention in the TAF. Have opted to maintain VCSH at KCHS/KJZI for now. Extended Aviation Outlook: Mainly VFR conditions expected. Brief periods of flight restrictions will be possible in showers and thunderstorms through the weekend.
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&& .MARINE...
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Today: Weak high pressure remains across the local waters, while a frontal system will be situated to the north and northwest. S and SW winds expected this afternoon as the sea breeze develops with speeds as high as 15 kt and gusty. Seas will average 2 or 3 feet. Tonight: A cold front and wave of low pressure will approach, and with some tightening to the gradient and inflow into storms over land areas, southerly winds will be as high as 15 or 20 kt with higher gusts. Seas will build up to another foot or so from the daylight hours. Tuesday through Saturday: A stalled front will linger across or in the vicinity through at least Saturday. This pattern will lead to variable winds, especially in showers and thunderstorms. Outside of convection, wind speeds will be less than 15 knots with seas less than 4 feet.
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&& .TIDES/COASTAL FLOODING... Since there will be modest southerly winds occurring prior to the high tide close to 12 midnight in Charleston Harbor, and tides will still be far above predicted levels, there remains a chance of very minor salt water flooding. We will closely watch tidal trends through the day and this evening, to see if a Coastal Flood Advisory could become necessary. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE... TIDES/COASTAL FLOODING...

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