Light snow with minor accumulations is in the forecast for Friday night and Saturday, leading the National Weather Service to issue a Winter Weather Advisory for parts of the northern Cumberland Plateau.
As of Friday morning, a Winter Weather Advisory had been issued for Fentress and Pickett counties to the west of Scott County. However, Scott, Morgan and Campbell counties further east were not included in that advisory.
Differences of opinion: The Winter Weather Advisory covering only a portion of the northern plateau reflects a difference of opinion between two offices of the National Weather Service. Fentress and Pickett counties are covered by the NWS office in Nashville, along with the rest of Middle Tennessee. Scott, Campbell and Morgan counties are covered by the NWS office in Morristown, along with the rest of East Tennessee. NWS-Nashville opted to issue a Winter Weather Advisory for its counties; NWS-Morristown opted not to … at least for now.
Drilling down the difference: NWS-Morristown weather forecasters feel that only up to an inch of snow will fall across the northern plateau region. In a Hazardous Weather Outlook published Friday morning, forecasters there said that “light accumulations are possible…” for this area. In a Forecast Discussion, meteorologists said that “Up to one inch of snow is possible across the Cumberland Plateau and generally less than half an inch for portions of the north and central Tennessee valley,” while also pointing out that snow banding is possible but impossible to pinpoint until it develops.
By contrast, NWS-Nashville feels that up to two inches of snowfall, with some isolated higher amounts, will occur, which prompted the Winter Weather Advisory. In a Forecast Discussion published Friday morning, meteorologists there said that “Right now, highest snowfall amounts appear to be along the Upper Cumberland with 1-2 inches possible. Can’t rule out a few localized spots reaching higher amounts, especially for those in our northern Plateau counties.”
Likelihood: There is uncertainty regarding just how much snow will fall. Both forecast offices of the NWS have only a 50% chance of snow in their forecast. However, most forecast models show 1 to 2 inches of snow for the northern plateau, including the usually reliable short-range HRRR model.
Timing: The Winter Weather Advisory for Fentress County takes effect at 10 p.m. EST Friday evening. It isn’t likely that troublesome snow shower activity will begin that early at least on the eastern side of the plateau, but the timing is difficult to nail down because the snow showers are convective in nature and will develop as the night progresses — whereas the timing would be easier to predict if the snow was being produced by a more organized weather system that was progressing across the region.
There is the possibility of ongoing scattered rain or snow showers in the plateau region by late afternoon or early evening. However, it appears that snow showers will not increase in coverage until after midnight. It’s likely that snow shower activity will begin to wind down by late Saturday morning.