409 FXUS62 KCHS 112328 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 628 PM EST Tue Dec 11 2018 .SYNOPSIS... High pressure will prevail through Thursday. A storm system will affect the area Thursday night into Saturday. High pressure will then return early next week. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Late afternoon update: minor tweaks to a few temps, otherwise forecast on track. A weakening ridge will build over the Southeast, allowing flow overhead to become semi-zonal. At the surface, high pressure centered over the FL Panhandle will gradually move eastward, moving closer to our area. This will allow dry weather to prevail. Though, some high clouds may start overspreading the area from the northwest late. Good radiational cooling with light winds will allow temperatures to fall below freezing in most locations away from the immediate coast. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... Wednesday and Thursday: Dry/quiet weather conditions are anticipated through mid week under a mainly zonal flow aloft and a large area of sfc high pressure that becomes centered over the Southeast United States on Wednesday, then slowly shifts northeast toward the Mid- Atlantic coast and offshore by late Thursday morning. Latest guidance then suggests a coastal trough developing off the Florida peninsula Thursday afternoon, but moisture return north will be lacking initially, thus all areas are expected to remain dry into Thursday evening. Overall temps should gradually modify Wednesday through Thursday under mostly sunny skies. In general, highs should range in the mid/upper 50s Wednesday, then lower 60s on Thursday. Wednesday night lows will remain chilly under clear skies and light/calm winds. In general, temps should dip into the mid 30s well inland to lower 40s along the coast. Thursday Night through Friday: A high amplitude trough of low pressure will dig over the Central United States initially, before transitioning into a cut-off low over the Deep South, then eventually Southeast United States. At the sfc, low pressure will track over the South-Central United States and Deep South this weekend with an eastward advancing cold front that eventually shifts through the region early this weekend. Ahead of the system, strong isentropic ascent along with a warm front should help produce abundant clouds and showers beginning across Southeast Georgia and inland Thursday night before spreading over the remainder of the area Friday. Strong dynamical forcing associated with the arrival of a low, mid, and upper-lvl jet along with h5 shortwave energy should produce a wide swath of rain/showers over the region, especially as a plume of deep-layered moisture characterized by PWATs up to 1.50- 1.80 inches advects over the region in advance of the low pressure system. Many areas could see upwards to 1-2 inches of rainfall accumulation this weekend. There are also indications of weak instability in the mid-lvls as the system shifts over the region, suggesting a few rumbles of thunder on Friday. Although the overall severe weather threat can not be ruled out completely, the risk will be very low given a lack of stronger or even modest instability. High temps should be warmest along coastal areas Friday, peaking in the mid/upper 60s. && .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 /00Z WEDNESDAY THROUGH SUNDAY/... VFR at KCHS/KSAV through 00Z Thursday. Extended Aviation Outlook: MVFR or IFR conditions are likely at both CHS and SAV terminals Thursday night into Saturday morning as rain/showers occur with a passing low pressure system. VFR conditions should then return at both terminals by Sunday. && .MARINE... Tonight: High pressure will spread across the Southeast, with the surface pressure gradient keeping winds no higher than 15 kt. Seas within 20 nm will subside about a foot overnight. For the GA waters beyond 20 nm, a Small Craft Advisory will remain in effect until midnight due to seas ranging from 4-6 ft. After midnight, these seas will subside to 4-5 ft. Fairly quiet marine weather expected Wednesday and Thursday while high pressure prevails. However, southerly flow will increase ahead of an approaching low pressure system this weekend. Latest guidance suggests the pressure gradient will become enhanced over all waters by Friday, resulting in Small Craft Advisory level conditions over offshore waters starting late Thursday night, then over most waters on Friday. 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... AVIATION... MARINE...