930 FXUS62 KCHS 140622 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 122 AM EST Thu Feb 14 2019 .SYNOPSIS... High pressure will build across the region this evening, then will persist into Friday. A series of low pressure systems will impact the area this weekend into early next week. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Early this morning: Satellite imagery shows that the back edge of the shield of high clouds has slipped offshore and clear skies will prevail for the next several hours. With calm winds, excellent radiational cooling conditions will be in place. Temperatures have already started dropping, with some upper 30s already being reported inland. && .SHORT TERM /6 AM THIS MORNING THROUGH SATURDAY/... Thursday and Friday: Ongoing forecasts remain on track and required only minor adjustments. High pressure will shift offshore Thursday and will provide mostly sunny skies/high temperatures ranging from the mid/upper 60s inland to the upper 50s/lower 60s close to the coast. Between the offshore high and an approaching cold front, despite increasing high clouds Friday high temperatures will range from the lower 70s at most inland locations to the lower/mid 60s at the coast. Thursday night: Low temperatures ranging from the lower/mid 40s inland to the lower 50s on the beaches will accompany rain-free conditions. Friday night, the surface cold front will stall north of the region, and low pressure will develop/track east along this boundary. Warm air advection, isentropic ascent and moisture transport ahead of this feature should push isolated/scattered showers into at least northern/western counties, especially after midnight. However, timing/coverage of overnight showers remains somewhat uncertain. Otherwise, clouds will hold temperatures in the 50s. Saturday: Low pressure passing north of the region should push showers through parts/all of the area, depending on the operational model solution. Ongoing PoPs range from around 50 percent north to slight chance south. However, location/coverage of showers remains uncertain, with alternate solutions ranging from most measurable precipitation remaining just north of the region to showers overspreading much of the area. Also of note, ongoing forecasts maintain a warm sector with southwest winds and high temps in the lower/mid 70s. However, the Wednesday 12z operational NAM12 suggests that a shallow backdoor cold front, aided by precipitation/ associated cooling, could push into SC counties with cooler temps in the mid 50s to lower 60s Saturday afternoon. Because subtle model differences translate to significantly different conditions, confidence in Saturday forecasts remains low. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... A complicated and unsettled pattern is expected. The 00Z models show a much different solution than earlier, which means this is a low confidence forecast. A stationary front may be over or near our area Saturday night. Models then show a southern stream storm or two developing Sunday through Tuesday, with the bulk of energy either just brushing us or passing to our north. The potential impacts will need to be better defined as this time period gets closer. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... VFR conditions expected to prevail at KCHS and KSAV through 06z Friday. Extended Aviation Outlook: VFR into Friday. A series of storm systems could bring periods of flight restrictions beginning Saturday. && .MARINE... This Evening and Tonight: High pressure will continue to spread across the region this evening, then become centered over the Southeast United States late, resulting in a relaxed gradient over all coastal waters. Conditions will remain well below small craft advisory levels for all coastal waters through the overnight period. In general, northwest winds will become north and decrease to around 10 kt or less. Seas will range between 1-3 ft, highest offshore. Extended Marine: High pressure located over the Southeast Thursday morning will move offshore in the evening, continuing an eastward movement into the night. Then, a complex scenario will develop and will introduce uncertainly into wind/sea forecasts late weekend into early next week. A cold front will approach from the northwest Friday, then will stall north of the waters Friday night. A weak low pressure will develop and track east along the the front/north of the waters Friday night through Saturday. This low will move offshore late Saturday into Saturday night and will push a cold front into the waters. The front will again stall by Sunday, this time over or close to the waters. A series of southern stream storms may then bring impacts to the area next week. The tracks of individual surface lows and the resulting position of the wavering, quasi- stationary front will determine wind direction/speed and associated seas. Small Craft Advisories may be needed for some of the waters on Saturday due to stronger SW winds and elevated seas, and periods of SCA conditions are possible across at least some areas through early next week. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ NEAR TERM...BSH SHORT TERM...SPR LONG TERM...MS AVIATION...BSH/SPR MARINE...DPB/SPR