974 FXUS62 KCHS 070742 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 342 AM EDT Fri Oct 7 2022 .SYNOPSIS... High pressure will prevail until a cold front moves through the area early Saturday. High pressure will then return for the weekend and early next week. && .NEAR TERM /THROUGH TONIGHT/... Today: Aloft, west-southwest flow will prevail as a trough progresses across the Great Lakes region. At the surface, weak high pressure will sit across the region as an upstream cold front shifts into the Appalachians. Overall, another quite day with a dry forecast and very little in the way of cloud cover. Low-level thickness values continue to trend higher from previous days and will be supportive of temperatures in the low 80's at KCHS. This should result in highs in the low to mid 80s for southeast South Carolina and mid to upper 80s for southeast Georgia. We should see another solid sea breeze in the mid to late afternoon hours as well with only light west to southwest flow ahead of its development. Tonight: The advancement of the upstream cold front will slow as it moves into the lee of the Appalachians. The front should enter inland portions of the forecast area late, but won't clear the entire region by sunrise Saturday. The forecast continues to be dry, with lows in the mid to upper 50s away from the immediate coastline. && .SHORT TERM /SATURDAY THROUGH MONDAY/... Saturday morning a cold front will be positioned just offshore of the southeastern coast, having moved through the region Friday night. High pressure will build in behind the cold front. Zonal flow to broad troughing will prevail aloft. This cold front is not forecast to be particularly strong, therefore little will change between Friday and Saturday. Temperatures Saturday are forecast to be in the upper 70s across southeastern SC and low 80s across southeastern GA. With clear skies and light and variable winds, Saturday night looks poised to be a good set up for radiational cooling. Overnight lows on Saturday are forecast around 50 far inland, with upper 50s to near 60 along the coastline. Sunday and Monday look to follow a similar pattern of building high pressure at the surface and broad troughing to zonal flow aloft. High and low temperatures will be right around normal. Subsidence from the building high pressure will allow the sunny and rain-free pattern to persist. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... High pressure will continue to prevail at the surface through next week. A cold front is forecast to move through the region late week, bringing with it the first chance of precipitation in the forecast period. Temperatures are forecast to be right around normal. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... The main forecast challenge through sunrise will be the potential for fog at the terminals. Model guidance supports at least some shallow fog, with the potential for MVFR visibilities. The KCHS, KJZI, and KSAV TAF's have been adjusted to feature a TEMPO group for MVFR conditions roughly from 10-12z. Any fog that develops will dissipate quickly after sunrise and then VFR conditions will prevail through 06z Saturday. Extended Aviation Outlook: Prevailing VFR. && .MARINE... Today through tonight: Light flow will prevail this morning before turning onshore later this afternoon with the development of the sea breeze. winds closer to the land/sea interface should top out in the 10-15 knot range. Overnight, southwest winds in the 5-10 knot range will prevail ahead of a cold front approaching from the northwest. Seas are expected to be in the 1-2 ft range through the period. A cold front will be positioned in the vicinity of the coastal waters Saturday, having passed through the land zones Friday. As high pressure builds in at the surface behind the front a slight surge in the winds is forecast. Conditions are forecast to remain below Small Craft Advisory criteria, with northeasterly winds around 15 knots with gusts to 20 knots currently in the forecast. High pressure will then prevail across the marine zones into early next week, with generally tranquil marine conditions forecast. && .TIDES/COASTAL FLOODING... Upcoming evening high tide (~7 pm): At Charleston, the astronomical high tide is 6.55 ft MLLW. Tidal departures are still running positive around 0.6-0.8 ft despite coastal winds not being particularly favorable. It appears near certain that Charleston will reach minor flood stage this evening, and could approach moderate flood stage. A Coastal Flood Advisory will almost certainly be needed. At Fort Pulaski, the astronomical high tide is 8.39 ft MLLW. While high could approach minor flood stage, current thinking is that it will fall short in the 9.2-9.4 ft MLLW range. A Coastal Flood Advisory could be needed there if minor flooding becomes more likely. Astronomical influences from the upcoming full moon will lead to elevated tide cycles this weekend and into next week. Over the weekend, both morning and evening high tides could have moderate to major coastal flooding along the Charleston and Colleton County coasts, then with the morning high tides through mid-week. From Beaufort County to McIntosh County, minor to moderate coastal flooding will be possible with the morning and evening high tides this weekend, then with the morning high tides through mid-week. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...BSH SHORT TERM...CPM LONG TERM...CPM AVIATION...BSH/CPM MARINE...BSH/CPM TIDES/COASTAL FLOODING...