462 FXUS62 KCHS 071504 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 1004 AM EST Fri Jan 7 2022 .SYNOPSIS... High pressure will prevail through the weekend. A strong cold front will approach the region Sunday night and should push offshore by Monday. Colder high pressure will then build over the region and will prevail into late next week. && .NEAR TERM /THROUGH TONIGHT/... High pressure will continue to build across the area today in wake of a departing cold front. Plenty of dry air and subsidence found in soundings will maintain quiet weather. Near full insolation is expected, however there will be some passing high clouds at times this afternoon. Temperatures will be much cooler, only peaking in the lower to middle 50s. Tonight: The center of sfc high pressure is forecast to shift across the central Appalachians late, settling over WV/VA by daybreak Saturday. Ridging high pressure across the forecast area should support light NE winds. Lingering cool thicknesses, clear sky, and light winds will result in temperatures to steadily cool through the night. Using a blend of MOS, low temperatures are expected to range from the upper 20s far inland and across the Francis Marion National Forest, with 30s across the coastal counties. && .SHORT TERM /SATURDAY THROUGH MONDAY/... Saturday and Sunday: High pressure to our north will shift from the central Appalachians through the Mid-Atlantic and offshore. As a result, winds will turn toward the northeast, and the marine influence featuring increasing moisture/moderating temperatures will spread into the region, initially into SE GA then spreading north along the coast with time. A strong cold front will approach the region associated with a broad H5 trough digging over the U.S. Midwest. A line of deep moisture ahead of the front will creep into the forecast area from the west Sunday evening and showers will spread east throughout the night. With little surface instability over land, mention of thunder has been limited to only the coastal waters; however, the coastal communities could hear a rumble of thunder Sunday night. Influence from an upper jet and proximity to its right-front quadrant will strengthen upper forcing late Sunday night which is when the bulk of the rainfall is expected to occur. Categorical pops are highlighted during this time frame across just about the entire forecast area. Saturday's highs will range from the lower 60s south of I-16 across SE GA to the lower/middle 50s most other locations. Saturday night lows should average upper 30s/lower 40s and in the low to mid 50s along the coast. Southerly winds will push Sunday's high temperatures into the low to mid 70s inland and mid/upper 60s on the beaches. Lows will remain mild overnight as WAA and south/southwesterly flow strengthens, with temps ranging from the mid 50s to near 60 degrees across the forecast area. Monday: By Monday morning, the cold front is expected to be positioned just offshore and much of the rainfall will have cleared with the exception of some lingering showers along the immediate coast. Otherwise, high pressure will build into the region in the wake of the cold front. Dry air will replace the moist airmass and skies will clear by the afternoon. Even with full insolation, CAA will limit highs about 10-15 degrees cooler than Sunday; only reaching the upper 50s/low 60s. Lows will dip into the 30s Monday night over most of the forecast area. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... The influence of cool, dry high pressure will dominate the long term forecast. A mostly rain-free forecast is expected with nearly sunny skies each day. Cloud coverage and rain chances are expected to increase by the end of next week ahead of a weak front. Tuesday will start off with much colder and below normal temperatures, which are expected to gradually warm to near normal by the end of next week. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... High pressure should steadily build across the region in the wake of the cold front today, providing VFR conditions through the 12Z TAF period. Northwest winds at KCHS and KJZI may gust to around 20 kts until mid-morning. By mid-day, northwest winds should settle to around 10 kts and will persist through this afternoon. This evening, ridging high pressure will result in winds to veer from the NE, strengthening during the pre-dawn hours tonight. Extended Aviation Outlook: Increasing probabilities for flight restrictions affecting all terminals Saturday night/Sunday. IFR conditions are possible with showers Sunday night, followed by a return to VFR conditions, accompanied by gusty N/NW winds on Monday. && .MARINE... Today: Northwest winds and elevated seas should steadily decrease through the day, with Small Craft Advisories expected to come down at 11 AM. This afternoon, winds will average in the 10-15 knot range with seas down to 2-3 feet. Sfc high pressure is forecast to ridge SW across the marine zones tonight. As the ridge builds, winds will shift from the NE and will increase to 10-15 kts with gusts near 20 kts. Seas should remain generally between 2-3 ft, with 3 ft becoming more common by late tonight. Saturday through Wednesday: As high pressure shifts over the Mid- Atlantic region Saturday, winds will veer E/NE, and a coastal trough will develop causing the surface pressure gradient to tighten. Guidance holds winds and seas just below Small Craft Advisory levels, but low-end SCA conditions cannot be ruled out. Sunday, ahead of an approaching cold front, winds will shift out of the south and will likely increase to SCA levels late Sunday/early Monday as the front begins to push offshore. As high pressure builds over the waters in the wake of the front, seas will build to 3-5 feet across the nearshore waters out 20 nm, and up to 5-7 feet from 20 to 60 nm. Winds and seas will remain elevated through the remainder of the period, with conditions improving late Wednesday. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...Small Craft Advisory until 11 AM EST this morning for AMZ330- 350-352-354-374. && $$ NEAR TERM...ETM SHORT TERM...BRM LONG TERM...BRM/SPR AVIATION...BRM/NED MARINE...BRM/NED