Area Forecast Discussion
Issued by NWS Columbia, SC

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000 FXUS62 KCAE 210715 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 315 AM EDT Wed Aug 21 2019 .SYNOPSIS... High pressure in the Atlantic will direct a moist south flow into the forecast area through the rest of the workweek. Then, an upper-level low will cross the Northeast and its associated cold front will push into the forecast area over the weekend. The pattern supports high chance to likely probabilities of showers and thunderstorms this weekend. The front may linger over the forecast area early next week, keeping a chance of showers in the forecast. && .NEAR TERM /THROUGH TONIGHT/... The upper trough that helped support showers and thunderstorms during the early morning hours will be north of the forecast area today and tonight. There will be h5 ridging and h85 westerly flow in its wake. The main thunderstorm support will be strong heating and weak convergence into a lee trough this afternoon. The high- resolution models suggest little thunderstorm coverage. We continued the forecast of just chance pops. Moderate instability indicates a few of the thunderstorms could possibly contain strong wind. The thunderstorm chance should further diminish this evening with the loss of heating. The temperature guidance was close with highs mainly in the lower 90s and lows in the lower 70s. Expect peak heat index values around 100 this afternoon. && .SHORT TERM /THURSDAY THROUGH THURSDAY NIGHT/... Flatter upper level flow is expected during the day Thursday, but a lee surface trough will be in the area. Shortwave energy will then approach from the north during the evening, and scattered convection will again be possible. Temperatures will be seasonal with highs in the low 90s and lows in the low 70s. && .LONG TERM /FRIDAY THROUGH TUESDAY/... On Friday, an upper level trough will swing through the Northeast with the associated cold front pushing into North Carolina. Scattered convection will therefore be possible on Friday, but there is a much better chance of rain on Saturday and Sunday as the front stalls over the area. With PWAT values above 2 inches and expected high convective coverage, there will be a threat of heavy rainfall and flooding. The front will be dissipating on Monday, but high pressure off the coast will cause onshore flow which will then continue to fuel convection. Onshore flow is expected to persist on Tuesday, so at least diurnal convection can be expected. Temperatures will cool somewhat over the weekend and into the beginning of next week with highs mainly in the 80s. && .AVIATION /07Z WEDNESDAY THROUGH SUNDAY/... Expect mainly VFR conditions during the 24-hour TAF period but there will be a chance of thunderstorms. The upper trough that helped support showers and thunderstorms during the early morning hours will be north of the forecast area today and tonight. There will be h5 ridging and h85 westerly flow in its wake. The main thunderstorm support will be strong heating and weak convergence into a lee trough this afternoon. The high- resolution models suggest little thunderstorm coverage. The thunderstorm chance was too low to include in the terminal forecast at this time. Moderate instability indicates a few of the thunderstorms could possibly contain strong wind. The thunderstorm chance should further diminish this evening with the loss of heating. There is a diminished fog risk because of weak instability and mixing. The NAM and GFS MOS and most SREF members maintain VFR conditions. EXTENDED AVIATION OUTLOOK...Widespread showers or thunderstorms may occur Saturday and Sunday associated with a front moving into the region. Otherwise, there may be stratus and fog during the early morning hours with scattered mainly afternoon and evening thunderstorms. && .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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