Area Forecast Discussion
Issued by NWS Charleston, SC

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365 FXUS62 KCHS 230301 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 1101 PM EDT Wed May 22 2024 .SYNOPSIS...
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High pressure will persist into late week. Diurnal convection and hot temperatures expected during the holiday weekend. A cold front might bring impacts to our area on Tuesday.
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&& .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
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Tonight: Conditions will remain similar to the previous night with sfc high pressure persisting across the local area under a ridge axis aloft. The first half of the night will experience favorable radiational cooling conditions with winds decoupling and becoming light/calm under clear skies. However, some cirrus will continue to shift across the region overnight, limiting cooling potential a few degrees after midnight. Patchy fog becomes a possibility a few hours prior to daybreak, mainly across inland areas of southeast South Carolina where sfc temps dip into the lower 60s. However, high clouds and drier grounds should limit greater fog coverage late. Elsewhere, lows in the mid 60s are anticipated across southeast Georgia while temps remain in the upper 60s/lower 70s closer to the beaches.
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&& .SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY/... Thursday: The day will begin with the H5 ridge along the coast, shifting east through the afternoon. A shallow H5 trough will slide over the southern Appalachians during the afternoon. At the sfc, a wavy front should remain across the Ohio River Valley, with moisture pooling to the east. Short term guidance indicates that a weak sea breeze may develop Thursday afternoon. However, with poor lapse rates lingering llvl CIN should keep the forecast area dry. High temperatures are forecast to range around 90 degrees. Friday, the H5 heights will remain generally zonal with a weak trough across the Coastal Plain in the afternoon. Isolated to scattered showers and thunderstorms are forecast to develop along a sea breeze Friday afternoon. Given sfc conditions in the low 90s and dewpoints in the upper 60s to low 70s, a wide field of instability should develop during the heat of the afternoon. Saturday, models indicate that broad H5 trough will develop across the Southeast U.S. At the sfc, a weak trough is expected to form along the coast, reinforced with an afternoon sea breeze. High temperatures will once again favor values in the low 90s. However, dewpoints should increase, generally ranging in the upper 60s to around 70. Deep moisture convergence and instability along and west of the sea breeze should support isolated to scattered thunderstorms. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... Mid-level ridging should build across the region on Sunday. The forecast area will remain between deep low pressure over the Ohio River Valley and high pressure over the eastern Gulf of Mexico. This pattern should provide the region with deep south winds. Given the ridge overhead, showers and thunderstorms should hold off until the afternoon and evening, forming along the sea breeze. Sunday is expected to be the hottest day, with mid 90s possible across the forecast area. The H5 ridge will remain across the forecast area on Monday. Sfc high pressure over FL is expected to ridge northward across the CWA. The forecast will continue to feature isolated to scattered showers and thunderstorms with highs in the low 90s. A cold front is forecast to impact the region on Tuesday. At this time, the forecast will feature PoPs in the high chance range. With the late arrival of the front and convection, temperatures may reach the low 90s. Wednesday, temperatures may range a bit cooler, with values in the upper 80s. Slight dryer conditions should result in lesser coverage of afternoon and evening showers and thunderstorms. && .AVIATION /03Z THURSDAY THROUGH MONDAY/... VFR conditions are expected at CHS/JZI/SAV terminals through 00Z Friday. However, patchy fog could briefly produce MVFR vsbys between the 09-13Z Thursday time frame. At this time, JZI includes TEMPO MVFR vsbys during this time while CHS/SAV remain VFR. Extended Aviation Outlook: Mainly VFR through Thursday night. Brief flight restrictions are possible due to showers/thunderstorms each afternoon/evening beginning on Friday. && .MARINE...
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Tonight: High pressure will persist across local waters, leading to a fairly relaxed pressure gradient. Winds should remain around 10 kt or less, slowly veering from southeast to south/southwest late. Seas will be no higher than 1-3 ft, slowly subsiding through the night as well. Extended Marine: High pressure should yield typical summer-time weather across the forecast area. In fact, a sea breeze is expected to develop each afternoon through the holiday weekend. A cold front may arrive on Tuesday, bringing an increase in thunderstorm activity. Otherwise, conditions should remain below Small Craft Advisory conditions. Rip Currents: On Thursday, the combination of astronomical influences from the Full Moon and a small swell will lead to an enhanced risk of rip currents at all of our beaches. The in-house Rip Current Calculator continues to indicate a Moderate Risk, while the Rip Current MOS points to a Low Risk. For consistency, we maintained the Moderate Risk. Rip currents are most likely at Tybee Island.
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&& .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...DPB SHORT TERM... LONG TERM... AVIATION...DPB MARINE...DPB