320 FXUS62 KCHS 230038 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 838 PM EDT Sun Jun 22 2025 .SYNOPSIS... High pressure will remain across the Southeast U.S. the first half of this week, then shift into the Atlantic for the second half of the week. Surface troughing should form over the region the second half of this week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... Rain-free conditions will persist overnight, although an isolated shower/tstm could develop closer to the west wall of the Gulf Stream early Monday. It will remain warm tonight with lows dropping into the lower 70s inland to around 80 at the beaches and Downtown Charleston. Winds should go calm later this evening as the sea breeze decays and the boundary layer decouples. This could allow a few spots to drop into the upper 60s where radiational cooling can be locally maximized, but these instances should be pretty isolated. Some shallow ground fog could develop just before daybreak, mainly south of I-16 and up into the far southern South Carolina coastal counties where 1000 hPa condensation pressure deficits will be at their lowest. No major reductions in visibilities are expected. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... The mid-levels will consist of a very strong ridge over the eastern half of the U.S. with an embedded 598 dam High over the Mid-Atlantic States. The embedded High should weaken to about 594 dam and shift over the TN Valley by Wednesday. While we will have very high heights over our area, the highest will remain just to our north and northwest. At the surface, High pressure will be located over the Southeast U.S. through Wednesday, gradually weakening. Though, there are hints that weak surface troughing could start to form over our region on Wednesday. This pattern will usher plenty of moisture into our region. But this won`t equate to much convection because the aforementioned ridge and High will limit the convective potential. Models keep Monday fairly dry, with at most a lone weak shower along the sea breeze. Tuesday, the models hint at maybe isolated weak convection along the afternoon sea breeze. Wednesday, should be a repeat of Tuesday. Overnights should be dry. But the main story will be the heat. The combination of heights and 850 mb temperatures will yield above normal temperatures. Highs will easily climb into the 90s each day, except cooler at the beaches due to the afternoon sea breeze. Tuesday appears to be the hottest day in the short term with some inland highs hitting the upper 90s and making a run for the 100 degree mark. Heat indices will also climb well into the 100s each day. As of right now, heat indices hit Heat Advisory criteria (108 degrees) on Tuesday. But we`re concerned the inland dew points will lower in the afternoon due to the westerly winds more than the models are showing, which would cause heat indices to be a few degrees lower. This will continue to be monitored. Also, low temperatures will remain very mild and only fall into the low to mid 70s. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... The strong mid-level ridge initially in place over our region should weaken by the end of the week. Likewise, the surface High will shift away from our area and be replaced by surface troughing. This will cause a gradual increase in diurnal convection. Temperatures will remain above normal into the weekend. && .AVIATION /01Z MONDAY THROUGH FRIDAY/... 23/00z TAF Discussion: KCHS/KJZI/KSAV: VFR prevails through Monday. Some shallow ground fog could develop just before daybreak Monday, especially at KSAV, but no meaningful reductions in vsbys are expected. Extended Aviation Outlook: Mainly VFR. There could be brief flight restrictions due to afternoon/evening convection Thursday and Friday. && .MARINE... Tonight: A typical southerly wind regime for summer will persist. Speeds will average 10 kt or less with seas 1-2 ft. Monday through Thursday: High pressure will remain across the Southeast U.S. the first half of this week, then shift into the Atlantic for the second half of the week. Surface troughing should form over our region the second half of this week. But a typical summertime wind pattern will be in place. Each day, winds should back with the formation of the afternoon sea breeze. The strongest winds will be along the land/sea interface and across the Charleston Harbor (with it`s passage). Each night, winds will veer and increase as the nocturnal jet sets up, especially closer to the coast. Seas will generally be 2 ft. && .TIDES/COASTAL FLOODING... The new moon is Tuesday night, which will yield higher astronomical tides. Winds should be from the SW, which would limit tidal anamolies. So while Coastal Flooding (mainly for the Charleston tide gauge) is not forecasted at this time, it won`t take much for it to occur, prompting an advisory. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$