The winter of discontent continues tonight with the next winter storm in this back-loaded winter that just doesn’t seem to want to give up the ghost.
Winter storm warnings are in effect for the entirety of the northern Cumberland Plateau region this afternoon, as cold air begins to creep southwest. Much of the rest of East Tennessee, outside Scott, Morgan, Campbell and Claiborne counties, remains under a winter storm watch, as forecasters at the National Weather Service in Morristown continue to evaluate just how far eastward the impacts of this storm will extend. Expect a final call for those areas, including the Knoxville metro area, in the next hour or so.
For now, the NWS is forecasting up to a quarter-inch of ice and 1-3 inches of snow for the eastern side of the plateau (Scott/Morgan counties), and a tenth of an inch of ice and 2-5 inches of snow for the western side of the plateau (Pickett/Fentress counties). The reason for the differences is because different NWS offices are responsible for the plateau. NWS-Nashville is siding with more snow and less ice, while NWS-Morristown is siding with more ice and less snow.
I was critical of NWS-Morristown last week for not giving enough credit to models that indicated we would see up to a half-inch of devastating ice here on the edge of the plateau. But this time around, their forecast is more in line with what the most reliable models have shown for the past couple of days.
Details as far as how much we’ll see of each precipitation type remain in doubt, but the GFS and NAM models have consistently shown most of our precipitation falling in the form of freezing rain and sleet, followed by a little snow on the back end of the system. Today’s midday run of the NAM model shows 0.25” freezing rain for the northern plateau, along with almost a half-inch of sleet. That’s somewhat in line with the same model’s run from earlier this morning, which showed just over a quarter-inch of freezing rain and nearly 0.7” of sleet.
One thing the midday run of the NAM model did do was bring in colder temperatures aloft a little more quickly. Whereas this morning’s run showed no snow for the northern plateau, the afternoon run showed three inches of snow, with less sleet.
The midday run of the GFS model, meanwhile, also brings in colder temperatures aloft more quickly. The result is very little freezing rain on this particular portrayal of what’s going to happen; the GFS shows less than a tenth of an inch of ice, with nearly 0.4” of sleet and almost three inches of snow. The run of the GFS from earlier this morning showed twice as much ice, about the same amount of sleet, and less snow.
Snow is better than sleet and ice — particularly ice — any day of the week, so I think these model changes are changes we can all get behind, but it remains to be seen whether they’re reliable.
At 2 p.m., Oneida was registering a temperature of 60 degrees, as was Crossville, while Clarksville was reporting 36 degrees. So the colder air is certainly headed this way. We’re running a little behind schedule, based on what models were projecting. The temperature should really begin to drop in the next couple of hours. It’s worth keeping an eye on to see if anything changes. For now, meteorologists still expect a changeover to frozen precipitation shortly after midnight tonight.
Update I (2:38 p.m.): Perhaps evaluating the midday model guidance (discussed above), NWS-Morristown’s updated winter storm warning for the northern plateau ups snow totals to 2-4 inches. Ice accumulation is still forecasted to be up to a quarter-inch. Not surprisingly, the NWS went with a winter weather advisory for the rest of East Tennessee, calling for ice accumulation up to a tenth of an inch and snow/sleet accumulations generally less than two inches.