Area Forecast Discussion
Issued by NWS Knoxville/Tri Cities, TN
Issued by NWS Knoxville/Tri Cities, TN
448 FXUS64 KMRX 051752 AFDMRX Area Forecast Discussion National Weather Service Morristown TN 1252 PM EST Fri Dec 5 2025 ...New DISCUSSION, AVIATION... .KEY MESSAGES... Updated at 1235 PM EST Fri Dec 5 2025 - Occasional drizzle could continue in the northern TN valley through this evening. Otherwise, dry but dreary conditions will be the norm through the first half of Sunday. - Next system arrives Sunday night into Monday with very light precipitation. Some low elevation snow could occur in the north, but accumulations and impacts should be negligible. && .DISCUSSION... Issued at 1235 PM EST Fri Dec 5 2025 A northern branch jet will remain situated from the Arklatex region, ENE through our forecast area and into the mid-Atlantic seaboard through Saturday. With saturated low levels lingering in the northern half of our CWA through at least late tonight, I wouldn`t be surprised if areas of drizzle continue to show up from time to time through late tonight. Otherwise, the forecast through Saturday should be largely dry, though quite cloudy. The next chance of precipitation looks to be Sun night into Mon morning. We`ll be sandwhiched between a southern stream disturbance ejecting ENE from the southern plains along the subtropical jet, and a stronger shortwave over the Great Lakes associated with the polar jet during this time. There`s no strong surface cyclogenesis in the southeast so any precip with this system will be driven by jet dynamics aloft and should be light in nature. There`s some indication that precip could miss us to the north and south, focused with stronger jet support on either side of us. However, model soundings show at least some moisture present and higher resolution models do show some light precip. Kept the high NBM PoPs because I think the likelihood that we get something more than a trace of precip is pretty high, but this will certainly be a high PoP/low QPF scenario. Regarding the chances of winter weather, I did leave some snow in the forecast for low elevations but certainly don`t believe there will be impactful snowfall. Between the low QPF and the soundings showing the potential for more of a seeder-feeder snowfall setup, there`s very low chances of anything sticking, much less causing impacts. For the higher elevations of northeast TN, the NW flow behind this shortwave could result in a couple of inches through Monday evening but that`s a low confidence part of the forecast right now. Tue and Wed look dry, but the next system arrives Wed night into Thu, with better chances for widespread rainfall. && .AVIATION... (18Z TAFS) Issued at 1235 PM EST Fri Dec 5 2025 Lack of air mass change and continued saturation of the lowest 2-3k ft means there shouldn`t be much change in the flight categories and cloud through the 18z TAF period. The forecast reflects that. There could be some brief MVFR conditions this afternoon but I would expect CIGS to drop back into IFR territory tonight. Most uncertain part of the forecast is whether we fog in overnight or not. Have some reduced VSBY in at all sites but confidence is low on whether that`s enough of overdone. A return to VFR conditions doesn`t seem likely until the tail end, or perhaps after, the 18z TAF period. && .PRELIMINARY POINT TEMPS/POPS... Chattanooga Airport, TN 36 52 34 55 / 0 0 0 10 Knoxville McGhee Tyson Airport, TN 37 49 31 51 / 0 0 0 10 Oak Ridge, TN 34 48 30 50 / 0 0 0 10 Tri Cities Airport, TN 36 45 28 49 / 0 0 0 10 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ DISCUSSION...CD AVIATION...CD