Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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501 FXUS62 KCHS 052238 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 638 PM EDT Sun May 5 2024 .SYNOPSIS... Atlantic high pressure will remain across the Southeast U.S. through much of next week. A cold front will move through the region late week bringing cooler conditions heading into next weekend. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... This Evening: Few to scattered showers/thunderstorms will persist for the next hour or two, initiated by a seabreeze circulation shifting well inland, then drifting behind to the east-northeast within a modestly unstable environment characterized by SBCAPE around 1500-2000 J/kg and PWATs near 1.5 inches. A strong thunderstorm with gusty winds and small hail can not be ruled out if it initiates along or just west of the seabreeze well inland (mainly southeast South Carolina near the I-95 corridor), where DCAPE values around 500-800 J/kg reside. However, the window of opportunity is rather small and activity will likely come to an end around sunset as instability weakens with the loss of diurnal heating. Overnight: Much like the previous night, conditions will become dry for most areas while weak mid-lvl shortwave energy exits to the north/northeast and a brief period of ridging resides across the local area for much of the night. Patchy fog could develop across some locations well inland late where skies are clear and winds are light for much of the night, but coverage will likely remain limited to locations that have experienced rainfall. At this time, any mention of fog remains out of the forecast, but could eventually be included. Lows will remain mild, ranging in the mid 60s inland to upper 60s/lower 70s near the coast. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... Larger scale ridging will be in place through the early part of the week with surface high pressure off the coast stretching across the Bermuda region. That said, convectively induced short-wave trough (originating with convection moving through the lower/middle Mississippi River Valley today) will advance through the Carolinas and mid Atlantic region Monday afternoon into Monday night. Temperatures warming into the 80s away from the coast and dewpoints in the lower to middle 60s will yield a decent amount of instability with MLCAPE values running 1000-1500 J/Kg Monday afternoon and minimal convective inhibition. Modest forcing with the wave in tandem with the inland pressing sea breeze should kick off scattered to numerous showers and thunderstorms across the forecast area while additional showers and storms develop through central Georgia into the Midlands and potentially press into the region later in the day. We will be maintaining 60 to 70 pops across inland areas Monday afternoon with convection slowly diminishing Monday night...but higher (categorical) pops may eventually be needed as convective evolution becomes more clear in the near term. Severe weather threat looks low overall although relatively slower moving storms and healthy PWAT values could present a heavy rain threat. Short-wave trough moves off the Atlantic coast Monday night followed by low amplitude ridging building through the southeast CONUS for Tuesday and Wednesday. Quieter conditions anticipated, although some spottier shower/thunderstorms are possible across the Carolinas to the mid Atlantic Tuesday and again Wednesday, although it`s tough to pin down pops/timing at this juncture. We have maintained some lower end precip chances across southeast South Carolina on Tuesday followed by dry weather on Wednesday as mid level warming/capping takes shape. Otherwise, temperatures will continue to warm through midweek as upper level ridging builds through the region and convective coverage dwindles with highs in the middle to upper 80s Monday to the lower 90s by Wednesday. Heat index values remain well below any heat related headline criteria, but daytime high temperatures will be pushing record high readings by Wednesday. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Unseasonably warm temperatures carry into Thursday with highs in the lower and potentially middle 90s. Again, heat index values will remain below headline criteria. But record high temperatures are a good possibility again Thursday. Otherwise, low amplitude upper level ridging will hold through the beginning of the long term period before stronger short-wave energy dives out of the Midwest and down through the mid Atlantic/southeast CONUS late in the week into early part of the weekend. Associated surface cold front will swing down into the region...slated to move through the forecast area on Friday. This will be our next decent chance for showers and thunderstorms...possibly as early as Thursday afternoon from anything that gets going upstream, although the higher precip chances come Friday with the boundary moving through. Quieter and cooler (70s to 80s) weather settles in for next weekend with possibly some showers lingering across the southern part of the forecast area Saturday in the vicinity of the boundary. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... KJZI: Overnight, VFR conditions are forecast. There is a slight chance of some patchy fog, but overall conditions don`t look to conducive. The crossover temperature at KJZI is 68 degrees, with low temperatures not forecast to get below that. Monday, a leftover MCV will approach the terminals from the west. Current TAFs aren`t advertising any mention of thunder, but this will likely need to be added in future TAF issuances. KCHS/ KSAV: Overnight, VFR conditions are forecast. There is a slight chance of some patchy fog, but overall conditions don`t look to conducive. The crossover temperature at KCHS/ KSAV is 66 degrees, with low temperatures not forecast to get below that. Monday, a leftover MCV will approach the terminals from the west. Current TAFs aren`t advertising any mention of thunder, but this will likely need to be added in future TAF issuances. Extended Aviation Outlook: Overall conditions will remain VFR through the week although brief flight restrictions are possible at the terminals Monday and to a lesser extent Tuesday. && .MARINE... Tonight: Marine conditions will remain quiet with high pressure centered off the coast of New England favoring a south-southeast wind around 10-15 kt locally this evening, followed by a gradual weakening to around 10 kt or less as winds turn more directly south overnight. Seas will generally range between 2-3 ft. Monday through Friday: Atlantic high pressure will maintain relatively benign conditions over the local marine waters. Southeasterly winds in the morning will back slightly during the afternoon and evening hours each day as the sea breeze develops. Winds will average 10-15 kt with seas 2-4 ft. Winds will increase toward the end of the week as a cold front approaches. Small Craft Advisory conditions are possible as gusts approach 25 kt, but look marginal at this juncture. && .CLIMATE... May 8: KCHS: 93/1986 May 9: KCHS: 95/1963 KSAV: 95/1962 && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...DPB SHORT TERM...Adam LONG TERM...Adam AVIATION...Adam/Haines MARINE...Adam/DPB