Area Forecast Discussion
Issued by NWS Columbia, SC
Issued by NWS Columbia, SC
062 FXUS62 KCAE 172346 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 746 PM EDT Tue Sep 17 2024 .SYNOPSIS... An upper level low pressure system will move slowly east across the area through Thursday. This will lead to scattered showers and seasonable temperatures. High pressure will build into the area from New England over the weekend into early next week with dry and seasonable temperatures expected. && .NEAR TERM /THROUGH WEDNESDAY/... Key Message(s): - Occasional light shows expected, mainly from I-20 north. The surface low has degraded to a trof this evening, pretty much bisecting the eastern portion of the CWA from the western portion. on the west side, plentiful cloud cover and occasional showers are expected as synoptic scale lift from the upper low spinning around the upstate tries to overcome the lack of instability. With the low looking like it wants to start slowly shifting eastward, differential vorticity advection will support enough upward motion to keep the isolated showers going overnight, and in fact potentially increase in coverage after midnight. The areas most likely to stay dry will be the eastern midlands further away from the upper low and the deeper moisture. && .SHORT TERM /WEDNESDAY NIGHT THROUGH THURSDAY NIGHT/... Key Message(s): - Scattered showers and seasonable temperatures. Upper level low over the Upstate SC will move slowly east during the period. By Thursday afternoon the long wave trough axis should be along the Carolina coast. Precipitable water increases to 1.75-1.95 inches especially across the north Midlands and Pee Dee through Thursday night. Models show short wave triggers rotating around the upper low, with the strongest short wave Wednesday morning through the afternoon. Warm advection ahead of the trough should provide additional lift. Instability appears weak with HREF cape less than 1000 J/kg. Can`t rule out isolated thunderstorms especially in the east Midlands Wednesday afternoon. Otherwise, expect scattered showers and seasonable temperatures in the low to mid 80s. Persistence with lows in the low to mid to mid 60s Wednesday night. With the trough near the Coastal Plain Thursday afternoon, enough low-level moisture/weak instability for scattered showers and thunderstorms especially in the east Midlands and Pee Dee as weak short wave troughs rotate through. High temps again in the low to mid 80s. && .LONG TERM /FRIDAY THROUGH TUESDAY/... Key Message(s): -Trending drier for the weekend into early next week with seasonable temperatures Ensembles are in pretty good agreement with long wave trough along the Eastern Seaboard with ridge in the southern Plains slowly flattening and building to the east. Surface high building southwest from New England across the Carolinas into Georgia. The period appears dry with seasonable temperatures in the upper 70s to mid 80s for high temps. As the upper ridge to the west flattens, increase in some mid and high clouds at times. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... VFR conditions for much of the TAF period, with MVFR cigs possible near daybreak. With sunset some of the low to mid clouds have begun to diminish along with losing much of their vertical development. West of the terminals some vertical development remains as an area with weak forcing moves around the base of the low. Main concern for the period will be the low level moisture and potential for early morning stratus. Potential continues to increase for early morning MVFR cigs so have remained with mention at all terminals have cigs height and coverage remain uncertain...especially at AGS/DNL/OGB. As such have trended the TAF cigs lower at those terminals and will continue to monitor. Cig restrictions which develop will mix out by 15z with all sites VFR through the end of the period. Winds will be light and variable through mid morning then become south to southwest at 7 knots or less. EXTENDED AVIATION OUTLOOK...Early morning restrictions possible through Friday as lingering low level moisture persists. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...None. GA...None. && $$