Never under-estimate warm air advection, particularly here on the Cumberland Plateau. That was a general theme of the blog post I made late yesterday regarding the potential for light freezing rain tonight. And we’re starting to see that pan out already.
More on that in a moment. First, the entire northern plateau region — including Scott, Morgan, Campbell and Fentress counties in Tennessee, and McCreary County in Kentucky — is under a winter weather advisory from the National Weather Service. Specifically for Scott County, the NWS’s Morristown office has an advisory in place from 1 a.m. through 10 a.m. tomorrow for light freezing rain. The advisory states: “Light freezing rain expected. The ice will result in very slippery conditions on sidewalks, roads and bridges, including during the morning commute on Monday. Total ice accumulations of a light glaze are expected.” In a separate hazardous weather outlook published by NWS-Morristown, meteorologists continue to advise that no impact is expected to utilities, due to the very light nature of the rainfall that is expected.
As for the actual forecast, the NWS has a 30 percent chance of freezing rain during the overnight hours, a 60% chance of freezing rain between 7 a.m. and 9 a.m., before a transition to just rain after 9 a.m. as temperatures warm above freezing. Separately, in a briefing by the NWS this morning, meteorologists say there is a 34 percent likelihood of precipitation falling in Scott County while temperatures are below freezing, and highlights the potential for two-one hundredths of an inch of ice accumulation. That is notable, since the NWS last evening was calling for five-one hundreds of an inch of ice. Still, it will take only a very light glaze to cause some travel issues, and any drop of rain that falls with temps at or below freezing will become ice, due to the very cold ground it will be falling on.
So that’s the official forecast. With that said, I stated in yesterday’s post that one of the first indications we’d have of what to expect to night might come this afternoon, as we watch our temperatures climb. The southerly flow kicked in this morning, and our temps have quickly risen above freezing for just the second time in over a week (the first was on Wednesday, when we got into the mid 30s). And, as I alluded in that prior post, our temperatures are rising more quickly than surrounding valley locations. As of 1 p.m., valley locations in and around Oak Ridge and Knoxville were still at or just below freezing, while our temperature here in Oneida was 37 degrees.
Our forecast high for today was 38. With still a couple of hours of prime warming time before the sun starts to drop, we’re probably going to exceed that. The question then becomes how much temps can drop overnight, with clouds building in and a 5-15 mph south wind expected. Can we get below freezing tonight? The NWS forecast is for a low of 30.
The HRRR model, a frequently updating model operated by the NWS, has our temperatures warming overnight, after initially dropping back near freezing just after sunset. By the time we get into tomorrow morning, a couple of hours before sunrise, it has much of our area above freezing.
Temperatures are going to be borderline, but that’s only half the equation. The second half will be precipitation. Will we even see rain? Precip should be relatively light, but its timing remains in question. The low-resolution GFS and Canadian models have light freezing rain beginning in our area around 4 a.m. tomorrow morning. But the high-res NAM has it holding off until after 7 a.m. That could prove problematic for school administrators who are trying to make decisions on the school day. The HRRR will probably provide the most accurate depiction of what we can expect, but it isn’t yet within range, going only through about 6 a.m. tomorrow morning.
The bottom line: If I were a teacher, I’d make sure I had my lesson plans ready; if I were a student, I’d do my homework. With temps so borderline and precip so minor, it’s far from a certainty that we see any freezing rain Monday morning. With a southerly breeze expected throughout the night, I’m not at all convinced — as I’ve said all along — that we’re going to actually be below freezing if and when precipitation moves into our area tomorrow. Timing is another question mark, with some models bringing in some light rain between 4 a.m. and 7 a.m. but others holding it off until after 7 a.m.
Any freezing rain that does occur will be a travel concern. We aren’t going to have to worry about downed trees and power outages. And even if we see some travel issues in the morning, conditions will rapidly improve through the day, with temps rising into the 40s.
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.