Area Forecast Discussion
Issued by NWS Charleston, SC
Issued by NWS Charleston, SC
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385 FXUS62 KCHS 082017 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 417 PM EDT Sat Jun 8 2024 .SYNOPSIS... High pressure will prevail through the weekend, before a cold front moves through the area on Monday. The pattern is expected to turn more unsettled through mid to late next week. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... Afternoon analysis reveals surface high pressure from the Ohio Valley to the Gulf Coast, centered across the Gulf Coast region. Wedge of drier air/PWAT values an inch or less continues to edge through the southeast CONUS this afternoon and surface dewpoints have dipped into the 50s for most areas away from the coast. Thus, quiet weather is the rule with just a touch of Cu from Savannah into Beaufort County along the marine boundary. Tonight: Surface high pressure will weaken across the region while we see a bit of a rebound in deep layer moisture/PWAT values and surface dewpoints through the night. Nonetheless, conditions will remain quiet although with some mid and high cloud cover pressing into the region from the W/NW. Overnight/ early Sunday morning low temperatures should end up similar to last night...upper 60s to around 70, warmer along the coast. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... Sunday: The mid-levels will initially consist of High pressure in the northeast Gulf of Mexico and Low pressure north of the Great Lakes region. The High will weaken as time progresses, while the Low strengthens and forms a trough along the East Coast. At the surface, weak High pressure will initially be over the region in the morning. A cold front will approach from the northwest overnight, possibly making it to our northernmost counties by daybreak Monday. The High will bring our area mainly dry conditions into the afternoon. The combination of low-level thickness values, mostly sunny skies, and a sea breeze limited mainly to the coast will support high temperatures just short of record values. Highs should peak in the mid to upper 90s, except cooler at the beaches. However, dew points will be in the upper 50s to lower 60s away from the immediate coast, which will equate to heat indices at or just short of 100 degrees across our area. Moisture increases during the evening and overnight ahead of the front. The models point towards isolated convection, but disagree on the location. Therefore, we kept slight chance POPs closest to the front. While, SPC did put the northernmost portion of our area under a Marginal Risk for severe storms late at night, we feel like this may be overdone at this point. Low temperatures will remain mild, falling into the low 70s far inland and the mid/upper 70s near the coast. Monday: The mid-levels will consist of a positively tilted trough amplifying over the East Coast. At the surface, a cold front located over our northernmost counties at daybreak will slowly shift southeast during the day, likely becoming located offshore to our southeast by late at night. There will be a plume of moisture ahead of the front, with PWATs peaking around 2". Temperatures will few cooler compared to Sunday, with highs ranging from the upper 80s across our northernmost tier, to the mid 90s near the Altamaha River. Lift from the front and the sea breeze will combine with the moisture to generate afternoon convection. It appears the highest instability is along our GA coast, where MLCAPEs could reach 1,500 J/kg. Shear increases there, with DCAPEs possibly exceeding 1,000 J/kg. So a few marginally severe thunderstorms with damaging winds cannot be ruled out. We`ll also need to monitor the front, sea breeze, and boundary interactions as there is the concern backbuilding storms could lead to locally heavy rainfall, mainly along our GA coast. This will need to be refined with future updates. For now, we have chance POPs in the afternoon and evening. But models are showing hints that strong convection could persist through the night, especially closer to our entire coast. Low temperatures will range from the mid 60s far inland to the lower 70s near the coast. Tuesday: The positively tilted trough prevails over the East Coast. Meanwhile, a stationary front will meander just off our coast. Additionally, High pressure will be centered to our northwest. There is some uncertainty regarding whether moisture associated with the front will combined with the afternoon sea breeze to bring our area unsettled conditions, or if drier air from the High will overspread enough of our area to limit convection. We have chance POPs along the coast, especially our GA coast. But the models hint at it being drier as opposed to wetter. Highs will peak in the upper 80s to lower 90s. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... The general pattern is for a large, unorganized area of Low pressure to potentially develop somewhere in the Gulf of Mexico. Most models indicate that at least some of the deep layer/tropical moisture associated with this feature could spread northeastward toward our region, especially mid to late next week. We will continue to monitor the potential for locally heavy rainfall, but it remains too early to determine QPF/rainfall totals. Temperatures should be near to slightly below normal. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... VFR conditions will prevail at KCHS, KJZI, and KSAV through 18Z Sunday. Sea breeze will push across the terminals this afternoon, turning winds into the southeast along with an uptick in wind speeds. Winds go near calm tonight. Some mid and high cloud cover will be advancing into the region from the west through the course of the night and into Sunday. Extended Aviation Outlook: VFR through Sunday night. The chance for convection and periodic flight restrictions increases Monday through Thursday. && .MARINE... Tonight: Northeast winds 10 to 15 knots will persist across the coastal waters into the evening before veering around to the south/southwest and diminishing to 10 knots or less tonight. Seas 3 feet or less persist. Extended Marine: A cold front will approach from the northwest Sunday night, slowly moving through our waters on Monday, then meandering to our southeast Monday night through the middle of next week. Winds will initially surge Sunday night, but stay below Small Craft Advisory criteria. && .CLIMATE... Record High Temperatures June 9: KCHS: 99/1986 && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$