Area Forecast Discussion
Issued by NWS Columbia, SC

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966 FXUS62 KCAE 252150 AFDCAE Area Forecast Discussion National Weather Service Columbia SC 550 PM EDT Tue Jul 25 2017 .SYNOPSIS... An upper level trough will remain over the eastern U.S., but it will continue to be warm and humid across the area. This will keep thunderstorms in the forecast for the next couple of days with scattered afternoon and evening showers and thunderstorms. A weak cool front will stall north of the area today, then dissipated over the area on Wednesday. A stronger cold front expected to affect the area over the weekend bring more unsettled weather and cooler temperatures. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... Mean upper troughiness extending from New England SW to the Gulf Coast. Upper disturbance over west central GA moving slowly east, with indications of a weaker disturbance currently near the N SC/NC coast moving slowly SE. Atmospheric moisture gradient over our region, with precipitable water values 1.4 inches across our northern forecast area (FA) to 2 inches just south of the FA. Weak surface trough appears to be stretched across the central FA, with another surface boundary farther north over NC. Latest high resolution models indicate best chance of convection later this afternoon and evening will be across the southern portions of the CSRA and Midlands, where better moisture exists and ahead of the approaching upper disturbance. Coverage elsewhere may be limited by less moisture and some weak NVA. Model forecast soundings for CAE indicate fairly high LFC height/convect temp. Other isolated activity possible elsewhere, more likely near the weak surface trough or other boundaries. Latest satellite imagery indicating some enhanced cumulus, but no echoes appearing on radar yet. Think chance POPs southern CSRA/S Midlands in order, with slight chance elsewhere through this evening. Upper disturbance will continue to track east towards the CSRA and our southern FA overnight, while surface boundary to our north slips south into the FA. These factors may provide some continued possibility of showers or possibly an isolated thunderstorm late tonight. Models consensus indicates slight chance POPs in order. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/... A weak upper low along the AL/GA border this afternoon will slowly drift east and eventually move off the southeast coast Wednesday night. Additionally, a weak cold front will move into the area from the north and dissipate. Models indicate some surface convergence where these two feature meet...in the vicinity of the Midlands and Pee Dee Regions. This should provide enough forcing with daytime heating, temperatures around 90 for some afternoon showers/thunderstorms. Once again some of the storms could produce locally heavy rainfall as PW values are around 2.0 inches. Overnight lows will continue in the low to mid 70s. && .LONG TERM /THURSDAY THROUGH TUESDAY/... A slightly drier airmass is expected to advect into the area on Thursday as the models indicate ridge across the central/western U.S. tries to build a bit farther to the east into the Southeast. Have continued with slight pops across the area for Thursday. More changes as the mid/upper level pattern begins to change during the remainder of the long term period. Models indicate a vigorous s/w will dive southeast from Canada and to the Mid Atlantic coast by Saturday/Sat night. Additional weakness will develop along the east coast into next week. The cold front associated with this system will move across the region Friday night/early Saturday. This will increase the chance for showers and thunderstorms during the afternoon/evening hours. Will also need to monitor for the potential for severe weather with the cold front late Friday afternoon into early Saturday. The front will likely become stationary across GA/SC for much of the extended period. Temperatures will warm ahead of the front on Friday into the low/mid 90s...then cool down slightly for the remainder of the period into the mid/upper 80s. && .AVIATION /22Z TUESDAY THROUGH SUNDAY/... VFR expected this afternoon and early evening outside of any showers or thunderstorms. Scattered storms developing over portions of the southern CSRA and central Midlands late this afternoon. Drier air over northern and central SC should help limit areal coverage of convection somewhat in the Midlands, but given latest surface obs and radar loop, will mention thunder at CAE/CUB until around 00Z. Have also mentioned thunder at AGS/DNL/OGB, where better moisture exists along with an approaching upper disturbance. Included a VCTS mention until around 02Z at those sites. The upper disturbance will continue to track east towards our forecast area overnight and Wednesday, while a surface boundary over NC back doors down into our FA. This will provide a slight chance of showers, possibly an isolated thunderstorm, late tonight into Wednesday morning, along with a light easterly low level flow developing which may enhance low level moisture and provide a chance for lower CIGs. Increased chance of showers and thunderstorms Wednesday afternoon, mainly after 18z. EXTENDED AVIATION OUTLOOK...Mainly afternoon/evening thunderstorms, along with late night/early morning fog/stratus. && .CAE WATCHES/WARNINGS/ADVISORIES... GA...None. SC...None. && $$

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