Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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675 FXUS62 KCHS 020837 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 437 AM EDT Tue Jul 2 2024 .SYNOPSIS... A stalled front will linger near the area today before dissipating offshore. A hot and humid air mass will build over the region during the latter half of the week. A weak cold front could approach the region by Monday. && .NEAR TERM /THROUGH TONIGHT/... Today: Sfc analysis shows a stalled boundary/front currently draped east to west across the local area, from the South Carolina coastal waters through the Savannah, GA area and inland toward the Glennville, GA area. The environment remains very moist along and south of this feature (PWATS around 2+ inches), and continues to be a focus for showers and thunderstorms redeveloping heading into daybreak. Very little movement is expected of this feature this morning, given a lack of large scale features to steer the front. However, a slightly northward nudge is possible this morning before h5 shortwave energy rounds the eastern periphery of a ridge extending across the Deep South. Until this occurs, an onshore wind will continue to drive deep moisture onshore, leading to additional showers/thunderstorms during late morning into afternoon hours. Given PWATs approaching 2.25 inches and slow storm motions, some showers and thunderstorms could be heavy rainfall producers, particularly where moisture convergence is enhanced along the coast and the nearby front/boundary. WPC does currently have southern most portions of the South Carolina coast and much of southeast Georgia under a Marginal Risk for excessive rainfall, which falls in line with latest guidance and current trends. A few Flood Advisories are not out of the question given the setup. High temps today will be cooler with clouds and precip across the area, generally ranging in the mid-upper 80s, warmest across southeast Georgia. Tonight: Latest guidance has trended a bit more toward holding onto precip activity south of the front across southeast Georgia. However, diurnal heat loss should result in most convection to wane during evening hours. Additional showers and thunderstorms could redevelop across coastal waters and make a run toward the coast late. At this time, scattered showers and thunderstorms remain in the forecast across coastal areas through much of the night to account for this possibility. Low temps should range between the low- mid 70s inland to upper 70s near the beaches. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... High pressure off the mid-Atlantic coast will extend across the area on Wednesday, while a stalled front lingering nearby eventually dissipates. Aloft, a mid level ridge will build over the Southeast. Best potential for convection will be near the southern South Carolina coast and across southeast Georgia where deepest moisture resides. Further inland and to the north should not see as much activity. Highs will be in the upper 80s to lower 90s. Lows Wednesday night will range from around 70 inland to upper 70s at the beaches. Mid level ridge will dominate the pattern aloft Thursday and Friday. The surface will feature high pressure offshore and a trough of low pressure inland. Mainly just isolated to perhaps scattered diurnally- driven showers and thunderstorms are expected each afternoon and evening. Otherwise, temperatures and humidity will be on the rise. Highs will be in the low to mid 90s on Thursday, with heat indices topping out in the 100-105 range. Friday will be a bit hotter, and heat indices could approach local Heat Advisory criteria of 108 degrees in spots. Lows will be in the 70s. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... Guidance is in good agreement in the extended. Mid level ridge will hold over Southeast coast into the weekend, before weakening. At the surface, a trough of low pressure will persist inland with high pressure offshore. It should get a bit more convectively active than previous days with better instability and possibly weak upper support. Current forecast highlights chance PoPs (generally 40-50%) each day with coverage peaking in the afternoon and evening. We are continuing to monitor the potential for excessive heat. Highs temps mainly in the mid to perhaps upper 90s combined with elevated dew points will make it feel even hotter. Heat indices are forecast to approach or exceed 108 in many locations, with some potential to even hit 113. Excessive heat headlines could eventually be needed. Convection could disrupt temperature trends. && .AVIATION /09Z TUESDAY THROUGH SATURDAY/... KCHS/KJZI: TEMPO IFR cigs/vsbys are possible between 08-10Z this morning as light showers impact the terminals, but should gradually improve to MVFR around daybreak, then VFR by late morning. Thereafter, VFR conditions are anticipated Tuesday afternoon and should persist through 06Z. KSAV: Light showers will continue to impact the terminal during the next few hours. Regardless, TEMPO IFR cigs in place until 10Z this morning and could need to be extended a few hours as showers and thunderstorms drift back north near a front this morning. Otherwise, MVFR cigs/vsbys should prevail into at least mid morning hours after daybreak. Additional showers and thunderstorms remain possible at the terminal Tuesday afternoon with a nearby front and ample moisture in place. TEMPO flight restrictions will likely be needed in future TAF issuances to account for activity directly impacting the terminal. Outside of precip, MVFR cigs look to return by around 02Z Wednesday and could prevail through the night. Extended Aviation Outlook: Brief flight restrictions are possible in showers and thunderstorms, mainly in the afternoon and evenings through the period. && .MARINE... Today and Tonight: A fairly enhanced pressure gradient remains across local waters this morning, north of a stalled front/boundary currently positioned across southern SC waters. Northeast winds gusting up to 15-20 kt will be common through the morning north of this feature, while to the south and somewhat lighter southerly wind will prevail with gusts to around 15 kt. Seas could build upwards to 3-5 ft early today, highest across northern SC waters off the Charleston County coast. Overnight, the front should begin to drift south of local waters and/or dissipate, but showers and thunderstorms will continue to pose localized higher wind gusts and reduced vsbys at times until that occurs. Outside of this activity, winds should gradually weaken (10-15 kt) and seas should subside to 2-4 ft. Wednesday through Sunday: Northeast/east winds initially will turn southerly by late week. Marine conditions should stay solidly below small craft advisory criteria with speeds 15 knots or less and seas no higher than 4 feet. && .TIDES/COASTAL FLOODING... Favorable onshore winds and the approach of the new moon will lead to elevated tides over the next few days along the Charleston and Colleton county coasts. Tides levels could approach minor coastal flooding criteria of 7 ft MLLW in the Charleston Harbor. Further south, no tide issues are expected. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...DPB SHORT TERM...ETM LONG TERM...ETM AVIATION...DPB/ETM MARINE...DPB/ETM