258 FXUS62 KGSP 280558 AFDGSP Area Forecast Discussion National Weather Service Greenville-Spartanburg SC 1258 AM EST Sat Feb 28 2026 .WHAT HAS CHANGED... Guidance has trended toward more of a stratus event rather than a dense fog event overnight into Saturday morning. So confidence in widespread dense fog is decreasing. Confidence on possible wintry weather Monday into Monday night across the northern mountains and adjacent foothills is slightly higher. && .KEY MESSAGES... 1. Areas of fog and locally dense fog developing overnight, improving early this morning. Otherwise, dry and much warmer today through Sunday. 2. Well below normal temperatures for afternoon highs and possible wintry weather for the northern mountains and adjacent foothills into the I-40 corridor Monday into Monday night thanks to the development of Cold Air Damming. 3. Temperatures will rebound following the Cold Air Damming erosion starting next Wednesday with well above-normal temperatures sticking around through the end of the upcoming workweek. Rain chances remain in the forecast but confidence is relatively low. && .DISCUSSION... Key message 1: Areas of fog and locally dense fog developing overnight, improving early this morning. Otherwise, dry and much warmer today through Sunday. Weak in situ cold air damming will completely erode this morning, as sfc high pressure pulls off the East Coast. A southern stream upper trough with lots of dry air aloft will cross the area today. So once the CAD erodes, skies should clear out and result in pleasant, sunny conditions by mid-aftn. Before then, the latest guidance has trended toward favoring low stratus over fog, with patchy dense fog still possible in spots thru daybreak. But a Dense Fog Advisory is looking unlikely to be needed. With clearing skies expected across much of the area by early afternoon, temperatures are forecast to be around 10 degrees above normal. Thicknesses remain warm with added westerly/northwesterly downslope flow to bring highs around 15 degrees above normal Sunday, especially in the mountain valleys, foothills and Piedmont. Key message 2: Well below normal temperatures for afternoon highs and possible wintry weather for the northern mountains and adjacent foothills into the I-40 corridor Monday into Monday night thanks to the development of Cold Air Damming. A sprawling continental surface high (~1040mb) will shift across the Great Lakes Sunday night and set up shop over the northeastern CONUS by Monday behind a cold front the completes a full fropa across the CWFA late Sunday. In response, the synoptic set up supports the development of a Classical Cold Air Damming regime at the onset. At the same time, the southern stream jet will stretch from the Rockies through the Central Plains, and into the OH River Valley as multiple shortwaves reside within the mean flow. The leading wave is expected to arrive Monday morning and provide the first instance of precipitation across the region, especially over the North Carolina zones. Low-level WAA atop the cold dome will help to lock in the stable layer on Monday and allow for temperatures to make a drastic drop of 20-25 degrees compared to Sunday. Guidance are in better agreement with the strength of the CAD and would support thermal profiles cold enough for a light wintry mix, mainly in the form of freezing rain to develop over the typical colder spots during CAD in the northern mountains and adjacent foothills, with slightly higher confidence as the latest LREF guidance increased freezing rain probabilities to 35-55% for >0.01" and more guidance coming into slightly better agreement. Some of the deterministic guidance try to eek out a brief period of freezing rain over portions of the I-40 corridor late Monday, but confidence in that is much lower for this scenario. The surface high will be very transient as it shifts offshore the Northeast Coast into the northwestern Atlantic Monday night into Tuesday, allowing for more of an in-situ setup to take place Monday night into Tuesday. Guidance has sent the next shortwave a bit further north in the latest runs and has trended slightly drier for Tuesday, but moist upglide should be sufficient enough to produce some precip, but the colder air won't be as strong as the transition to an in-situ regime takes over, so all precip should be liquid. However, the area remains socked into CAD on Tuesday leading to temperatures remaining 5-10 degrees below normal for afternoon highs. Key message 3: Temperatures will rebound following the Cold Air Damming erosion starting next Wednesday with well above-normal temperatures sticking around through the end of the upcoming workweek. Rain chances remain in the forecast but confidence is relatively low. As the surface high continues to push further offshore over the northwestern Atlantic, the source for continued Cold Air Damming will be cut off and likely becomes more of a residual cold pool Tuesday night into the first half of Wednesday as the flow turns more out of the south-southwest. Anomalously high thicknesses will be present as anything left of a residual cold pool will quickly be eroded by low-level WAA, leading to much warmer temperatures by Wednesday. Wednesday is still iffy just based on how long it takes for the low cloud deck to scatter out during the day, but temperatures are expected to jump 15-20 degrees higher compared to Tuesday in the current forecast. Upper ridging offshore the Southeast Coast will keep the area well above normal through the end of the workweek with continued southwesterly moisture advection from the Gulf of America. As a result, daily PoPs remain in the forecast, but likely in the form of WAA showers, especially with coverage likely holding onto a diurnal trend. Wednesday remains mostly dry as that will be the transition day from the CAD setup into the WAA regime as it becomes fully established by Thursday and Friday. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... At KCLT and elsewhere: Stratus should persist at all our TAF sites thru this morning, with cigs mainly IFR, but possibly bottoming out in the LIFR range before sunrise. Guidance has backed off the widespread fog potential, so vsbys have trended toward mainly MVFR to IFR. Cannot rule out some vsbys around 1/2sm, especially at KHKY. Nothing is forecast to hold the IFR clouds in all day today, as NW winds and mixing should erode the stratus around midday to early aftn, mainly from NW to SE, leaving basically clear skies for the rest of the period. Confidence on the timing of cigs clearing to VFR is fairly high. Winds will remain light, starting out NE, then becoming rather VRB by midday and continuing thru tonight. Good radiational cooling conditions tonight may support at least patchy fog development, but guidance has trended toward less fog. For now, no vsby restrictions will be carried in the 06z TAFs. Outlook: Cannot entirely rule out redevelopment of fog at least in rural locations late tonight into Sunday morning. Otherwise, VFR thru Sunday. A strong cold air damming setup is expected Monday into Tuesday, which may bring showers and associated restrictions Monday into Tuesday. VFR conditions likely return Wednesday. && .GSP WATCHES/WARNINGS/ADVISORIES... GA...None. NC...None. SC...None. && $$ ARK/CAC