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Area Forecast Discussion
041 FXUS62 KCHS 240200 AFDCHS Area Forecast Discussion National Weather Service Charleston SC 1000 PM EDT SAT JUL 23 2016 .SYNOPSIS... High pressure will gradually shift offshore and persist through much of next week. && .NEAR TERM /THROUGH SUNDAY/... Isolated Diurnal convection this afternoon and evening dissipated after sunset and skies were mostly clear to partly cloudy across the forecast area with most of the lingering clouds of the cirriform variety. Mid evening mesoanalysis indicates a ribbon of somewhat higher pwats extend from the SC Midlands to the Pee Dee with most of the remaining mesoscale boundaries also up in this region. While a spotty/brief shower may still occur over our far nw tier of zones prior to midnight, we have silenced all pops on the evening update given radar and satellite trends. The weather should remain quiet overnight but will maintain 20% pops for beach communities mostly north of the Savannah River after 2 AM as the land breeze develops. Lows will range from the mid 70s inland to around 80 at the beaches, Downtown Charleston and around Lake Moultrie. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... Expect little change in the pattern through at least early week. A mid and upper level ridge will build over the area from the west, while a surface ridge will remain centered to the southeast. This will setup low level light south-southwest flow, becoming onshore near the coast each afternoon. Deep layer moisture remains marginal enough to keep slight chance to low end chance pops in the forecast for Sunday and Monday. Models in good agreement that moisture will be very marginal on Monday as mid/upper level dry layer develops over the region as the upper ridge builds slightly. Have kept slight chance pops Monday afternoon, with highest over the southwest/GA area. A slight increase in moisture is shown by models by Tuesday with slight to low end chance pops again during the afternoon. Given lack of upper forcing, main trigger for convection will continue to be the sea breeze and any low level/outflow boundary interactions. This time of year can never rule out possibility for isolated strong/severe storms, but widespread severe storms not expected. Temperatures will continue above normal with highs in the lower to mid 90s most areas away from the coast, and lows in the mid to upper 70s. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... Little change in the weather pattern expected through late week, with the primary surface features being Atlantic high pressure and a weak piedmont trough. Fairly typical summertime PoP scheme, with shower/thunderstorm coverage peaking in the afternoon and evening when instability is greatest. No more than 20-30% chances warranted at this time. Temperatures forecast to be above normal through the period. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... VFR. Isolated afternoon convection may be possible along the sea breeze/coastal corridor again sunday afternoon. Extended Aviation Outlook: VFR expected to prevail both sites through much of the week. Only brief flight restrictions possible each afternoon with isolated showers/thunderstorms. && .MARINE... Overnight: Low-level winds will veer to the southwest overnight as high pressure remains anchored well offshore. Speeds will increase to 10-15 kt with seas 2-3 ft with a few 4 footers well off the coast beyond 20 nm late. Sunday through Thursday: No highlights expected through the period. Atlantic high pressure will prevail with south-southeast winds through Monday, veering to south-southwest Tuesday through Thursday. Winds will be 15 knots or less and seas generally 3 feet or less. Isolated to scattered mainly late night through morning showers and thunderstorms each day. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. MARINE...None. && $$ SYNOPSIS... NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE...