Update: Dangerous cold outbreak looms

The National Weather Service is cautioning that the arctic cold outbreak currently in place over the eastern U.S. will intensify next week, even as snow chances continue to diminish.

The NWS’s Morristown weather forecast office issued a brief today saying that “precautions should be taken for extreme cold and long-duration sub-freezing temperatures, such as checking vehicle radiators, protecting water pipes at your house, and keeping children off frozen lakes and ponds.”

As of now, the NWS is projecting temperatures to stay below freezing from late Saturday until Wednesday afternoon. However, it is looking probable at this point that only the Tennessee Valley will warm to above freezing Wednesday afternoon.

This is significant. We often see colder temperatures than what we’ll see this next week. In fact, we got down to near zero last winter. But it isn’t often that we see such long-lived cold weather. Spending day after day below freezing without a reprieve from the sub-freezing weather is the sort of thing that causes pipes to freeze and radiators to bust.

There are two factors to consider here:

1.) After getting to 40 degrees tomorrow and Saturday, it’s looking likely that we’ll be below freezing from sometime Saturday night through at least Friday, Jan. 5. That’s more than 130 consecutive hours below freezing, which is very unusual in Tennessee.

2.) Not only will be below freezing, but it is looking increasingly possible that we won’t get above 28 degrees any day next week, through at least Thursday, which means that the entire 130 hours will be spent in a hard freeze . . . which is even more unusual in Tennessee. Model output statistics from the latest run of the GFS computer model show us getting to 26 on Sunday, 23 on Monday, 29 on Tuesday, 26 on Wednesday and 26 on Thursday, with lows of 12 on Sunday morning, 8 on Monday morning, 8 on Tuesday morning, 14 on Wednesday morning, 7 on Thursday morning and 7 on Friday morning.

This is a very impressive cold snap, not so much in terms of how cold temps will get, but how long the cold weather will last. It’s even more impressive considering there isn’t going to be snow on the ground. Usually a snowpack serves as a refrigerator to keep temperatures lower.

Exactly when this cold snap ends remains to be seen. As I mentioned in a previous post, there are signs of a sustained warm-up as we move closer to the middle of January, but as of now, models are showing the cold air lasting for at least the next 15 days. At this point, the question is when we’ll just manage to get above freezing. The midday run of the GFS model shows us just barely getting above freezing on Sunday, Jan. 7, after a solid week of sub-freezing temperatures. But the model doesn’t show the thermometer hitting 50 degrees through the end of its run on Jan. 13.

It isn’t a given that the cold air is going to relax as we get into the first weekend of January, either. The Canadian model shows bitterly cold temps holding on through the end of its run, which gets us into Jan. 8. That particular model is probably overdoing the cold; it has us getting below zero on several occasions during this cold snap. But it’s worth noting.

As for snow chances, those appear nil at the moment. It had once appeared that we would see the chance for some light snow and minor accumulations on New Year’s Eve, but that no longer seems like a possibility. The NWS has removed mention of snow from the forecast, and models are in agreement that there will be no snow anywhere south of a point between Somerset and Lexington over the weekend. The GFS doesn’t show a drop of precipitation through the end of next week. There are some storm signals a little further out but as of right now, those don’t appear to be snowmakers for the northern Cumberland Plateau region.


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