Area Forecast Discussion
Issued by NWS Charleston, SC

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000 FXUS62 KCHS 111732 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 1232 PM EST Tue Dec 11 2018 .SYNOPSIS... High pressure will prevail through Thursday. A storm system will affect the area Thursday night into Saturday morning, followed by another area of high pressure. && .NEAR TERM /THROUGH TONIGHT/... No changes with this update as everything remains on track. Rest of today: The sharp mid/upper level trough will continue moving off the coast this afternoon, with northwest flow prevailing as ridging builds eastward. At the surface, high pressure along the Gulf Coast will gradually shift eastward. Sunny skies are expected, allowing highs to reach the low to mid 50s. Tonight: Surface high pressure will draw closer and settle across the Florida, Georgia, Alabama area by late tonight. Clear skies should prevail until very late when a few cirrus approach from the west. Expect a cold night with lows below freezing for areas away from the immediate coast. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... Wednesday will be dry with high temps in the mid/upper 50s as deep layered high pressure prevails. Temperatures will warm several degrees by Thursday as the surface high shifts east and southerly flow develops. A few showers will be possible along the GA coast late in the day as an upper shortwave spurs a weak coastal trough to develop off the GA coast. A powerful closed upper low will move into the Arklatex region late Thursday night, spreading a large area of vorticity energy into the Southeast. Southerly 0-6 km flow will steadily strengthen Thursday night and Friday, with the resultant theta-e advection pushing PWats to 1.5-1.8" by midday Friday. Thursday night should see a steady increase in rain shower coverage due to strong isentropic ascent along and north of a warm front bisecting the area W-E. We are showing widespread showers and a few thunderstorms on Friday as several weak surface lows move through the area ahead of a cold front Friday evening. Given the unseasonably high PWats and deep forcing, many areas could pick up 1-2" of rain by Friday evening. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... Models have come into better agreement with the timing of the cold front, now showing it moving offshore late Friday night. Downslope flow will maintain high temps around 60 through Monday before a reinforcing cold front brings some cooler weather by Tuesday. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... 18Z TAFs: VFR. Extended Aviation Outlook: MVFR or lower conditions are likely Thursday night through Friday night as a storm system affects the area. && .MARINE... Today through tonight: High pressure will gradually draw closer to the area today, and northwest flow will prevail. Wind speeds will top out in the 15-20 knot range for the most part with some gusts to 25 knots in the outer waters. Overnight, winds will drop off a bit as the gradient weakens, becoming 10-15 knots. Seas will be 2-4 ft in the nearshore waters today, with some 5 footers possible near the 20 nm line in the Charleston County waters. Overnight, nearshore seas will be in the 1-3 ft range. For the outer waters 4-6 ft seas will continue through the evening dropping off to 3-5 ft late. The Small Craft Advisory for the outer Georgia waters continues through midnight. Fairly quiet marine weather expected Tuesday through Thursday as high pressure persists. Increasing southerly flow ahead of a cold front Thursday night through Friday will likely require Small Craft Advisories for most waters. Advisory conditions likely to persist into Saturday night or Sunday behind the cold front as fairly strong westerly winds occur. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...Small Craft Advisory until midnight EST tonight for AMZ374. && $$ NEAR TERM... SHORT TERM... LONG TERM...JRL AVIATION... MARINE... is the U.S. government's official web portal to all federal, state and local government web resources and services.