119 FXUS62 KCHS 040532 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 1232 AM EST Mon Jan 4 2021 .SYNOPSIS... High pressure will remain over the area through the middle of this week. A low pressure system should pass across the area Thursday into Friday, followed by another low pressure system potentially early next week. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Deepening low pressure will pull further off the Delmarva overnight and to the southeast of Long Island. This will allow for a trough or backdoor type cold front to approach from the north late, while cold high pressure attempts to build in from the west. This pattern will support steady winds veering from W to NW through the overnight hours, yielding weak cold air advection. Meanwhile, there will be some cirrus moving in from the west and southwest with a 130-140 kt upper level jet, while stratocumulus will advance into the region from the north in association with the surface trough that reaches north of I-26 by daybreak. This will impact mainly Berkeley County and northern Charleston County, where skies will become partly to mostly cloudy after 12 or 1 am. Elsewhere the cirrus will remain scattered and/or thin enough that mostly clear skies will suffice. Depending upon how much and how quickly the stratocumulus arrive will impact minimum temps north. But this are looks to be the "warmest", with lows mainly in the lower 40s, while just about everywhere else will experience lows in the mid and upper 30s. By far the coldest night for the new year so far. && .SHORT TERM /6 AM THIS MORNING THROUGH WEDNESDAY/... High pressure will remain the dominant surface feature through mid week. Expect dry weather with mostly clear skies, although a passing shortwave will bring some clouds to the area Monday night into Tuesday. Temperatures will average within a few degrees of early January normals. Highs will mainly be in the upper 50s to lower 60s. Lows Monday night will be in the upper 30s/low 40s, while lows Tuesday night fall to the mid/upper 30s. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... Dry high pressure will prevail across the Southeast United States Wednesday night into Thursday, but will then gradually shift off the Atlantic Coast with the approach of a low pressure system from the west Thursday afternoon into early Friday. A light southerly flow should develop across the Southeast United States on Thursday in advance of the system, favoring slightly warmer temps (highs in the low/mid 60s across the area). A cold front will then shift through the area late Thursday into early Friday, bringing scattered showers across most areas. Temps will become cooler post fropa within high pressure, resulting in highs generally ranging in the mid/upper 50s and lows dipping into the mid/upper 30s away from the coast during the weekend. Another low pressure system could impact the area early next week, with additional rain/showers across the Southeast United States. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... VFR at both KCHS and KSAV through 06Z Tuesday. Low probs of marginal MVFR ceilings for a few hours late tonight and early Monday at KCHS. Extended Aviation Outlook: VFR through Wednesday. The chance for flight restrictions will increase late Thursday due to showers associated with an approaching low pressure system and passing cold front. && .MARINE... Overnight: High pressure centered over the Deep South will build east over the Southeast U.S., as a surface trough/backdoor cold front will approach the SC waters from the north late. The quickest guidance indicates that the backdoor front could reach the Charleston Co nearshore waters around daybreak Monday. This pattern combined with weak cold air advection will support NW winds around 15 kts, with gusts into the low 20 kts from time to time. Wave heights are expected to range between 2-4 ft. Monday through Friday: Offshore flow will persist early this week, before winds veer to the north/northeast on Wednesday as high pressure slides towards the east coast. No marine concerns are expected with winds peaking no higher than 15-20 kt and seas averaging 1-3 feet. Winds/seas will then increase/build Thursday through Friday with the approach of a low pressure system and passing cold front. Small Craft Advisories could eventually be needed across a portion of local waters Friday and Friday night behind the front as west winds gust upwards to 20-25 kt while seas build around 6 ft offshore. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM... SHORT TERM...ETM LONG TERM...DPB AVIATION...JRL MARINE...