Area Forecast Discussion
Issued by NWS Charleston, SC

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880 FXUS62 KCHS 291442 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 1042 AM EDT Wed May 29 2024 .SYNOPSIS... High pressure will build in from the west mid to late week, passing overhead and then offshore over the weekend. && .NEAR TERM /THROUGH TONIGHT/...
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Minor changes with the temperatures and dew points, mainly to take the current observations and blend them into the forecast for this afternoon. Also, have minimal sky cover now, but expect fair weather cumulus to develop this afternoon. Otherwise, the cold front is continues to move farther way from our area. A broad, cyclonic flow aloft associated with longwave trough across the eastern CONUS will keep downslope trajectories in the lee of the Southern Appalachians in place again today. This will tend to temper somewhat the influences of slightly lower thicknesses and 850 hPa temperatures. Highs 88-92 derived from full sun thicknesses schemes were highlighted for all but the immediate coast where a weak sea breeze circulation will develop and remain pinned along or even just slightly offshore of the beaches. Tonight. Any lingering high-based cumulus will dissipate after sunset with the loss of insolation. The boundary layer looks to decouple by mid-evening resulting in calm/light surface winds even as a secondary, dry cold front crosses the area. These winds coupled with mostly clear skies and low dewpoints will support strong radiational cooling. The colder side of the 29/00z guidance was utilized to construct overnight lows with additional modifications made to support known mesoscale influences. Lows will range from 58-62 inland with lower 70s at the beaches and Downtown Charleston. Water temperatures over the Atlantic, rivers and other inland waterways are running in the upper 70s/lower 80s. The resulting specific heat influences from these warm water conditions will result in large thermal gradients over short distances near bodies of water.
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&& .SHORT TERM /THURSDAY THROUGH SATURDAY/... Mid level trough persists over the eastern U.S. until a stronger shortwave dives across the mid-Atlantic states Thursday night into Friday and the trough axis exits off the coast. This will allow ridging to build over the region for Saturday. The surface pattern largely features high pressure which will initially be centered to the northwest before it drifts east and eventually offshore. Relatively dry air mass and lack of any notable forcing mechanisms will maintain a mostly rain-free forecast. The exception being on Friday where a few showers/thunderstorms could impact the coastal southeast Georgia zones, but even this potential seems limited. It will be a pleasant few days with highs mainly in the mid 80s and plenty of sun. Low temperatures will span the 60s, with even some upper 50s across far interior areas Friday night. && .LONG TERM /SATURDAY NIGHT THROUGH TUESDAY/... Surface high pressure shifts offshore for the first half of next week. Mid level ridging also transitions offshore and weakens as a series of weak disturbances pass through. Still no notable day for precip, but should see a return to more seasonable diurnal rain chances. Temperatures are forecast to be within a few degrees of normal through the period. && .AVIATION /15Z WEDNESDAY THROUGH SUNDAY/... 29/12z TAF Discussion: KCHS/KJZI/KSAV: VFR through 30/12z. Extended Aviation Outlook: VFR. && .MARINE... Today: West to Northwest winds behind a departing cold front will back to southwest this afternoon as a weak sea breeze develops along or just offshore of the beaches. Winds will remain 10 kt or less with seas 1-2 ft. Tonight: Winds will begin to veer west and eventually north to northwest as a weak cold front pushes offshore. Winds will still hold below 15 kt, but will surge a bit after midnight. Seas 1-2 ft will build to 2-3 ft late. Thursday through Monday: No marine concerns through early next week. High pressure initially centered to the northwest will drift east and eventually offshore over the weekend. Wind speeds average 15 knots or less. Seas 1-3 feet early build to the 2-4 range over the weekend and into early next week. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE...