Update: Low snow potential for Thursday

Snow is likely to be in the air on Thursday, but as I noted yesterday and will reiterate today, this is likely to be a “snowstorm” of little consequence for anyone outside of the mountains.

A low pressure system will develop to our south late tonight and trek northeast through the day tomorrow, bringing precipitation to a large swath of the Southeast. This far north, any precipitation that falls will likely begin as snow — and perhaps even stay snow for the duration. (The current forecast from the National Weather Service is for an all-snow start, mixing with rain by mid-afternoon.) But there are big questions regarding how much precipitation will spread this far north, and temperatures.

First, the northward extent of the precipitation: There is going to be a relatively strong area of high pressure sliding southeast out of the northern Plains today. By tomorrow morning, it’s likely to be situated over the Midwest and then it’s just going to sit there. That’s going to dictate how far north the Gulf system can move. But, barring a surprise, it’s going to remain sufficiently south to avoid a tremendous impact to the northern Cumberland Plateau region.

Current modeling data from the GFS shows a tenth of an inch or less of precipitation in our neck of the woods. That isn’t enough moisture for much snow even if thermal profiles were perfect — and they’re far from perfect. The NAM is significantly wetter, showing up to a quarter of an inch of precipitation — but that’s still relatively little moisture, and the NAM shows us on the northern fringe of the precipitation field. The European model has come in line with the NAM in terms of precipitation, and shows about a quarter of an inch of precipitation across the northern plateau.

Next, temperatures: The NAM continues to keep us right around — or just below — the freezing mark through much of the day tomorrow. But, among the models, it is an outlier on the cold side. The GFS and European models take us into the mid 30s. By late afternoon, the European has us near 40 degrees. And the NAM3k, a higher-resolution version of the model, has us topping out at around 40 degrees tomorrow. The National Weather Service is forecasting a high of 36, which seems reasonable.

Keep in mind that we were in the 60s yesterday and, although we’ll be cooler, we’ll still be well above freezing today. So ground temperatures are going to be quite warm. Also keep in mind that we’re now in the latter stages of February. The sun angle is getting quite high in the sky, and it has a penetrating effect through cloud cover.

The bottom line is that light snow will have a very difficult time accumulating under a late February sun angle with above-freezing temperatures and a warm ground working against it. If snowfall rates are high enough, snow can certainly accumulate under all of those conditions … but then will begin to melt fairly rapidly once snowfall rates taper off.

Given the amount of moisture available tomorrow, and the dynamics in place, it’s unlikely that we’re going to see an especially prolonged period of enhanced snowfall rates that could create serious travel issues. It’s worth noting that the NAM, discussed in yesterday’s post, has backed off the significant accumulations that it was showing for our area — which is completely unsurprising. Most models are now showing anywhere from no snow to an inch or two of snow for our area, with the NAM still being on the high end … and still, most likely, being wrong.

Here is the snow accumulation map from the NWS:

As you can see, the NWS is calling for half an inch or less of accumulation for our area. Keep in mind that this would be on grassy or elevated surfaces. Absent a period of enhanced snowfall rates, which really isn’t expected, roads will just be wet tomorrow.

Not quite over: If you’re aching for spring, you’re going to have to wait just a little bit longer. It is looking likely that at least the first week of March will feature some of the coldest air, relative to normal, that we have seen this winter. Keep in mind that “colder than normal” means something entirely different in early March than it meant in early January. “Normal” is almost 10 degrees warmer in early March than it was in early January. Bitterly cold temperatures may not take over, but it does look like below-average temperatures will flood much of the continental U.S. by the end of this month and that will last into at least early March. Beyond that, we could see the below-average temperatures hang on until at least the middle of the month. As for snow … who knows? With plenty of cold air hanging around not too far to our north and waiting to be tapped, and an active storm pattern, anything can happen. It’s unlikely, but it’s certainly not impossible.

Another wet February: Only a little more than a tenth of an inch of rain was officially recorded in Oneida on Tuesday. That’s a surprisingly low amount, and it means we’re still in the single digits for February rainfall, at 9.83 inches. That’s still well above normal for the month thus far (2.49 inches), and it makes this February one of the wettest on record already (the fourth-wettest, to be exact, behind 2019, 2018 and 1953). But, with less than an inch of rain anticipated across the final 10 days of the month, it now seems extremely unlikely — almost a certainty, in fact — that we will not set a record for the wettest February for a third consecutive year. Still, 3 of our 4 wettest Februaries on record will have occurred in the last three years, and that’s very interesting.

Ben Garrett

Ben Garrett is a journalist from East Tennessee. He is publisher of the Independent Herald, a weekly newspaper serving the Big South Fork region of the Cumberland Plateau, with a sideline in website development and digital marketing. He is also an erstwhile blogger.

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