Area Forecast Discussion
Issued by NWS Columbia, SC

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000 FXUS62 KCAE 252156 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 556 PM EDT SUN SEP 25 2016 .SYNOPSIS... An upper-level ridge will continue to build east across the region tonight then move off the coast Monday. A cold front moving into the area tonight will stall across the area Monday providing a focus for scattered showers and thunderstorms. Another cold front will cross the area Tuesday night into Wednesday. The air mass behind this system will bring dry weather and more seasonable temperatures for the latter half of the week. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... A high amplitude upper-level ridge over the Mississippi Valley will continue to move slowly east overnight. Upper-level cut-off low over the Gulf coast area. At the surface, weak high pressure remains. Upper-level trough over New England with surface ridge building south along the Atlantic Seaboard will drive the cold front slowly southwest tonight. The air mass across the region will be marginally unstable. Convergence along the front and upper-level dynamics appear weak. Latest high-resolution models suggest little in the way of convection. Have forecasted slight chance pops. Overnight lows generally in the upper 60s to around 70 degrees. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY NIGHT/... Easterly low-level flow Monday resulting in deeper moisture. A stalled frontal boundary across the area will support scattered showers and thunderstorms in a weakly to moderately unstable air mass. Convection may focus near a sea breeze front in the east Monday. Deep upper low along the US/Canadian border Monday is forecast to move southeast into the Ohio River Valley by Wednesday. Thus will push a cold front through our area late Tuesday into Wednesday. We`re still seeing some timing differences with the 00Z ECMWF holding the upper low and cold front farther west. The 12Z GFS AND 12Z NAM are more progressive moving the cold front to the coast by the end of the day Wednesday. We have continued the chance for convection ahead of the front Tuesday then diminishing from west to east Wednesday as the cold front moves east of the Midlands. Temperatures are expected to remain above normal ahead of the front Monday and Tuesday, with highs in the mid to upper 80s and lows in the mid 60s to lower 70s. Should see slightly cooler temperatures Wednesday with highs in the low to mid 80s. && .LONG TERM /THURSDAY THROUGH SUNDAY/... Typical fall weather to spread across the region for the end of the week with seasonable temperatures. Dry and cooler air advecting into the region Thursday. Surface high pressure and stable conditions spreading across the region into next weekend. Deep upper trough crossing the eastern states. Overnight lows expected to range from the 50s to lower 60s with afternoon highs in the mid 70s to lower 80s. && .AVIATION /22Z SUNDAY THROUGH FRIDAY/... Weak convergence associated with a backdoor cold front moving into the area will help support stratus and fog development tonight. Most of the NAM and GFS MOS plus HRRR suggested mainly IFR stratus. Followed the GFS LAMP for the timing. Continued upper ridging should help keep moisture shallow. Nocturnal cooling should limit instability. The shower and thunderstorm chance overnight was too low to include in the terminal forecasts at this time. The diffuse front will remain in the area though the rest of the TAF period but some diurnal ceiling improvement should occur. The GFS and NAM MOS were in good agreement with generally VFR conditions developing during the day. Some increase in moisture will occur in an easterly flow Monday. The moisture and some convergence associated with the diffuse front in the area plus heating should support scattered showers and thunderstorms but still expect limited coverage with significant forcing associated with the next approaching cold front west of the area through the TAF period. Again, the shower and thunderstorm chance was too low to include in the terminal forecasts at this time. EXTENDED AVIATION OUTLOOK...A slow moving cold front will be in the area through Wednesday. Widespread stratus and fog may occur especially during and late night and early morning hours. There will also be scattered showers and thunderstorms. Drying may occur behind the front Thursday. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$ SYNOPSIS...99 NEAR TERM...99 SHORT TERM...99 LONG TERM...99 AVIATION...99

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