Update: Cold and getting colder, but what about snow?

The cold pattern that is entrenched across the Mid-South is about to get even colder as we exit 2017 and welcome 2018, but chances for an appreciable snowfall appear to be sketchy, at best.

It’s cold across East Tennessee this week. The National Weather Service at Morristown says we won’t get out of the 20s today in Oneida, and we’re headed for a low of 13 tonight. Temps will be back into the teens again tomorrow night, even as a short-lived warming trend begins.

We may see temperatures pushing 40 by Friday, but that will be just ahead of a surge of arctic air that could deliver even colder temperatures for the end of the weekend and the first few days of 2018.

As of now, the NWS is forecasting a high of just 26 degrees on New Year’s Eve, after a low of 13 Sunday morning. New Year’s Day is likely to see temps stay in the 20s as well.

The one question at this point is whether we see a storm system develop and push through the region as the cold air surges southward. The American chief of the global models, the GFS, had been indicating such a scenario, which would have resulted in a winter storm for much of the region. But it didn’t have much support from other global models, including the somewhat more reliable ECMWF.

A storm system on Sunday and Monday would be highly dependent on the timing of the trough that will deliver the cold air. If a low pressure system tries to develop to our south and the arctic air is too quick to arrive, the energy gets crushed and the storm system never materializes — at least not in our neck of the woods. And that is what the GFS is now suggesting.

That doesn’t mean we can’t see accumulating snow on Sunday and Monday; it just means the idea of a bonafide winter storm is probably off the table. Yesterday’s midday run of the GFS was showing 7-10 inches of snow for the northern Cumberland Plateau region with this storm system developing. Now it’s showing zilch.

However, even if the dynamics of a developed low pressure system aren’t on the table, there will be some moisture in the atmosphere, and the dynamics of the northwest flow that sets up as the cold air pushes in can also squeeze out snow showers, which could result in some light accumulations. Currently, the NWS is forecasting a 20% chance of snow showers on Sunday and Sunday night, followed by a high of 23 on Monday with a low of 8 degrees for Tuesday morning, Jan. 2 (and a high of only 28 that day).

Today’s early morning run of the GFS model is showing 1-2 inches of snow accumulation for the northern plateau, but the word of caution there is the midday run that followed it is showing about half that, and the overnight run that preceded it showed no accumulation at all.

Basically, there’s a chance for light snow accumulations on Sunday and Monday. At this point, that’s all it is — a chance. Anything that falls will be on the light side. However, with very cold ground temperatures in place, even a little bit could be enough to cause traffic hazards on New Year’s Eve, so it’s worth keeping an eye on.

The bigger story is the cold air. The GFS isn’t spitting out the insane numbers it was suggesting yesterday (with subzero nighttime temps) because it doesn’t have the snowpack in place that it was depicting yesterday. But the global models are in agreement that it’s going to be quite cold, hence the numbers that are popping up in the NWS’s official forecast.

This is reminiscent of the cold snap to greet the new year as January began in 2009. We were bitterly cold for about a week, even though there was no snow to show for it. We won’t be quite that cold for quite that long this go around, as the temperature pattern will probably relax a little bit next week before a fresh surge of arctic air filters in later in the week.

The question right now is what happens as that relaxation takes place. Some models are wanting to develop a storm system to the south that could result in a winter storm for our region. This morning’s run of the GFS suggested a scenario that would result in 4-6 inches of snow for our area around Sunday, Jan. 7 or Monday, Jan. 8, followed by temperatures that get as cold as -6. But that’s way out in the future — out in what legendary meteorologist James Spann calls voodoo land — so I wouldn’t count on that happening.

The bottom line: If you don’t like cold air, you’re probably going to want to go into hibernation for the next couple of weeks. It’s going to be very cold. We’ve seen colder weather in recent years than what we’ll see in the first 10 days of January, but when you consider the overall pattern between now and Jan. 12, it’s probably been a while since we’ve seen such a stretch of impressive cold weather. There are no serious indications that we’ll see much snow during this period, however, and there is good news — there are growing signs of a sustained warm-up as we head towards the middle of January.


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