378 FXUS62 KCHS 301120 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 720 AM EDT Mon Aug 30 2021 .SYNOPSIS... High pressure will prevail across the area through Tuesday. A cold front will then pass through the region during the middle of the week, before high pressure returns late week into the weekend. && .NEAR TERM /THROUGH TONIGHT/... Early this morning: Patchy to areas of fog will impact mainly the Georgia communities inland from the coast. The fog will linger through around 9 am, when condensation pressure deficits become less conducive. Locally dense fog is also a concern, so we have issued a Special Weather Statement through 10 am. Today: TC Ida will lift north into Mississippi as it's wind fields weaken considerably, while high pressure surface and aloft persists across the local area. The anticyclone aloft weakens a bit through the day, while the surface anticyclone initially right overhead, settle into the nearby ocean in the afternoon as a lee side trough develops. Moisture remains far below climo and just 70-75% of normal, while a capped atmosphere remains in place. This will again result in an unusually quiet day with the absence of any convection. Rather unusual for this time of year, with climo around 30-40% chances for showers and thunderstorms. There will be some cirrus in association with TC Ida that spreads through, along with few to scattered small cumulus as a result of just enough moisture trapped underneath the subsidence inversion. These clouds will have no bearing on max temps that look to peak 90-93F inland from US-17. The formation of the resultant sea breeze will hold temps to the mid and upper 80s closer to the Atlantic. Tonight: Ida will head toward the Tennessee Valley, as high pressure offshore the area drifts further away and slowly weakens. This occurs as the anticyclone aloft overhead slowly weakens and shifts offshore through the night. In spite of an increase in moisture, it's mainly aloft and there is still no forcing. Thus no reason to expect any rainfall. What we do foresee is varying amounts of high level clouds from Ida, while at least some lower marine induced clouds move onshore. That will allow for min temps to be a bit warmer than the past two mornings. There are hints of fog late far inland, but given the cloud cover we opted not to show anything at this time. && .SHORT TERM /TUESDAY THROUGH THURSDAY/... High pressure will gradually weaken on Tuesday as the remnant low of Ida tracks into the Tennessee Valley. The first half of the day will be dry, then moisture will steadily increase which could lead to the development of a few showers and thunderstorms in the afternoon, mainly over southeast Georgia. Kept rain chances around 20%. It will be the warmest day of the next several, with highs expected to peak around 90 or in the lower 90s away from the beaches. Lows Tuesday night will average in the mid 70s. As the aforementioned low continues to move northeast into the mid- Atlantic states on Wednesday, a trailing cold front will approach the area. PWats back above 2 inches and sufficient forcing for ascent will bring the highest rain chances of the week. Though its worth noting, there are mixed signals regarding coverage. The overall severe threat is fairly low as instability doesn't appear to be that impressive, but with slightly elevated wind fields the radar will bear watching. Temperatures will be right around normal. High pressure will build inland on Thursday following frontal passage. Most areas will be dry, however some lingering moisture will keep slight chance PoPs in the forecast early in the day, mainly closer to the coast. Highs will peak in the upper 80s to around 90. && .LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/... High pressure is expected to remain the dominant feature late week through much the weekend. Aloft, a mid level trough will push further away as a ridge expands into the region from the west. A relatively dry air mass and lack of any significant forcing mechanisms will preclude mentionable PoPs. It should be quite pleasant with lower dewpoints and temperatures averaging slightly below normal, especially earlier in the weekend. && .AVIATION /12Z MONDAY THROUGH FRIDAY/... The easternmost edge of extensive low stratus and fog will occur right near KSAV this morning. We presently have MVFR ceilings and visibilities through 1330Z, but IFR or even LIFR can't be ruled out. VFR weather will return thereafter. Both KCHS and KJZI look to remain VFR with the 12Z TAFs. Extended Aviation Outlook: Mainly VFR. Flight restrictions are possible in showers/thunderstorms on Wednesday. && .MARINE... Today and tonight: The marine area remains under the control of high pressure, despite it weakening with time. It does continue to steer TC Ida northward through the lower Mississippi Valley during today and toward the Tennessee Vally tonight. A weak gradient allows for the W and SW winds of 10 kt or less this morning to back to the S and SSW with sea breeze influences that are as much as 10-15 kt this afternoon. Similar winds remain for tonight, veering just a hair overnight. Seas will be just 2 or 3 feet, mainly in the form of swells. Tuesday through Saturday: High pressure on Tuesday will give way to a cold front approaching from the west on Wednesday. Winds and seas will ramp up as this occurs, and it is looking increasingly likely that Small Craft Advisories will be needed for at least a portion of the coastal waters, possibly including the Charleston Harbor, Wednesday afternoon into Wednesday night. Marine conditions are expected to improve thereafter following frontal passage. Winds will average 15 knots or less with seas 2-4 feet. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE...