**Update** Moments after this post was published, the National Weather Service in Morristown issued a winter weather advisory for Scott and neighboring counties, from 10 a.m. to 7 p.m. tomorrow, for 1-3 inches of snow.
Will Ol' Man Winter force local school systems to use their second built-in snow day of the season as classes are scheduled to resume after the Martin Luther King Jr. holiday? He certainly appears to be winding up to give it a shot.
Winter weather advisories are already out for Fentress and McCreary counties to our west and our north. The National Weather Service in Nashville is forecasting up to 2 inches of snow for Fentress County and the western side of the plateau, while the NWS in Jackson, Ky., is forecasting general amounts of 1.5 to 3.5 inches of snow across eastern Kentucky. The Tennessee advisory will take effect at 10 p.m. tonight; the Kentucky advisory at 7 p.m.
There is not yet a winter weather advisory for Scott County or anywhere else in East Tennessee. One will almost certainly be issued by mid-afternoon, with the NWS's forecast calling for a 60 percent chance of snow and 1 to 3 inches of accumulation in Oneida.
I blogged at length yesterday about the setup. A piece of energy associated with a cold front — it's what meteorologists refer to as a "clipper system" — will march across the state tomorrow morning, spreading light snowfall across the northern Cumberland Plateau beginning about daybreak. Ahead of the system, a southerly flow is ushering in much warmer air; we've already hit the freezing mark in Oneida this morning and will top out around 40 degrees — if not warmer. Behind the system, much colder air will invade the region once more; temps may drop into the single digits by Wednesday morning and struggle to get out of the teens Wednesday afternoon, especially if we have snow cover.
As I posted yesterday, clipper systems are notoriously moisture-starved because they aren't tapping the Gulf of Mexico, which is the primary source of moisture for storms in our part of the world. But they take advantage of thermodynamics to maximize their potential. This won't be a rain-to-snow transition, like we saw Friday, and ground temperatures will be quite cold, even though today's temps will climb to 40 or above. Additionally, with colder temperatures aloft, snow ratios better than the standard 10:1 are possible — in this case, it looks like we'll see ratios of around 15:1.
What will result will be light, "dry" snow with a low moisture content. It's not the kind of snow that clings to every surface in sight and creates a winter wonderland, and it's not the kind of snow that makes good snowmen or snowballs. It's snow that melts relatively quickly, even under the bitterly cold January sun.
At the same time, clippers are notorious for busting forecasts. The energy isn't as organized or as predictable as with an actual low pressure storm system. And, as NWS-Nashville pointed out in a forecast discussion yesterday, there's a minute difference between a dusting of snow and 2 inches of snow in cold weather events such as this.
Still, there is a pretty solid model consensus right now that most of Tennessee — including the northern plateau region — will see a couple of inches of snow, beginning around daybreak tomorrow.
I'm not convinced that we will see that much snow...but, then again, I'm not completely convinced that we won't see a little more. By later this evening, we should be getting a better idea of exactly what to expect.
As for schools, we all know it doesn't take two inches to force schools to close for the day. School buses and slippery roads in mountainous terrain aren't a good combination. It's possible — if not likely — that snow will not have begun falling by the time most drivers begin running their morning routes. But it will be apparent at that point, from radar and updated forecasts, whether this little snow system is progressing as expected. Administrators have several options, each of which they've utilized in the past — from delaying the start of classes by two hours to watch the forecast play out to going ahead and preemptively closing for the day based on the forecast.
Eye to the Sky is a weather blog by Independent Herald editor Ben Garrett. Garrett is a weather enthusiast who has long blogged about interesting weather on his personal website. He is not a professional forecaster or a meteorologist and information on this blog should not be considered a substitute for forecasts, advisories or other products from the National Weather Service.