Area Forecast Discussion
Issued by NWS Charleston, SC

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000 FXUS62 KCHS 242317 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 717 PM EDT Sat Oct 24 2020 .SYNOPSIS... High pressure will prevail today before an upper disturbance passes through tonight. A weak cold front will then move through Sunday night, followed by high pressure. A storm system is expected to bring impacts to the region late next week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... For the early evening update we have increased cloud cover based on satellite trends that show those thicker clouds starting to penetrate into our far interior Georgia zones. Additionally, the upstream showers are making steady progress toward the northeast, so we did raise PoP a bit for the mid and late evening across our Georgia counties. Overnight the convection will come at us from off the ocean with isentropic ascent, and also in association with the short wave from the west and southwest. We may need to raise PoP more in subsequent updates. Temps will be far above climo, and we will be close to record high min temps at all three climate sites for October 25. Previous discussion... A potent shortwave currently moving into western GA will move into central and eastern SC overnight. Decent upper level divergence will accompany the feature while unseasonably high PWs of 1.8" will overspread the area. Scattered to numerous showers will move in from the southwest late this evening and spread into southern SC after midnight. The best upper forcing will remain across our northwestern tier of zones closer to the shortwave where upwards of a quarter inch of QPF are possible by daybreak Sunday. Isolated thunderstorms are possible far inland as well as over the coastal waters. Increasing clouds and weak southerly flow will yield mild temps overnight with lows in the upper 60s to lower 70s. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... Sunday: A mid-level short wave will lift from south to north across the forecast area on Sunday. HREF indicates that a ragged band of showers and isolated thunderstorms will likely cover the CWA by daybreak, then exiting north through the daylight hours. Using the HREF for the timing and placement, PoPs will fall to 20-30 percent by 18Z, then falling below mentionable levels by Sunday evening. As the convection tracks to the north, partly sunny conditions should develop in the wake. High temperatures are expected to range from the upper 70s across the SC Lowcountry to the low to mid 80s across SE GA. Monday and Tuesday: The center of a strong H5 ridge is forecast to slide from N. FL to the western Atlantic, with 590 DM heights remaining over the CWA. At the sfc, the pattern will feature high pressure ridged over the western Carolinas with a trough over the Gulf Stream. Conditions appear dry on Monday, with isolated showers possible on Tuesday. Temperatures should slow warm trough the period. By Tuesday, high temperatures are forecast to generally range from the low to mid 80s. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... The mid-levels will consist of high pressure centered roughly over FL Tuesday night. The high will slowly trend eastward, into the Atlantic through Thursday. Meanwhile, a strong trough will approach from the west on Thursday, then pass overhead or just to our north on Friday. A cold front approaching from the west and a storm system developing in the Gulf of Mexico could combine mid to late week to bring various impacts to our area. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... Conditions favor the development of light to perhaps moderate rains for several hours overnight and at least Sunday morning, along with a low end potential for TSRA. Short wave energy will sweep through around 06-15Z Sunday, while weak low level forcing occurs from off the Atlantic due to the formation of a subtle coastal trough. At KSAV we have mostly low end VFR weather, but we are showing a tempo for MVFR conditions from 09-13Z Sunday, as per the High- Resolution guidance. Keep in mind that a larger window of MVFR is certainly possible though. We kept mainly low-end VFR conditions at KCHS, although we can`t rule out a period of MVFR conditions from around 09-15Z Sunday. Extended Aviation Outlook: Restrictive ceilings and fog may develop across the terminals around dawn Monday and Tuesday. A storm system could bring more flight restrictions starting on Wednesday. && .MARINE... Fairly weak winds expected tonight due to weak high pressure offshore. Seas over the offshore GA waters should drop below 6 ft by late tonight, after which the Small Craft Advisory for those waters will drop off. Sunday through Thursday: Swell associated with distant Hurricane Epsilon will subside early next week. Conditions across the marine waters are forecast to remain below Small Craft Advisory levels through the period. Generally, winds are expected to remain below 15 kts with seas between 2-4 ft. Rip Currents: Long period swells from distant tropical cyclone Epsilon will continue to arrive on Sunday. An elevated risk for rip currents will remain along the SC/GA coast. Swells are expected to decrease by Monday. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...Small Craft Advisory until 6 AM EDT Sunday for AMZ374. && $$ NEAR TERM... SHORT TERM...NED LONG TERM... AVIATION... MARINE... is the U.S. government's official web portal to all federal, state and local government web resources and services.