The Great Smoky Mountain Journal

Staff, Wire Reports

Posted: Sunday, January 21, 2018 07:30 PM

Weekend Winter System To Bring Snow, Very Cold Air to East Tennessee

The final days of 2017 could feature an East Coast snowstorm, just days after Winter Storm Ethan brought a Christmas clobbering to parts of New England and New York state.

Unfortunately, at this time, there is an extreme amount of uncertainty regarding whether this will actually happen, and if it does happen, the precise timing, and who may be affected.

Welcome to the world of winter weather forecasting.

What we do know is a strong southward plunge of the jet stream will sharpen up this weekend over the Great Lakes and East, providing the jet stream energy that could, in theory, spin up an East Coast storm

We also know that plenty of cold air will be in place over much of the central and eastern U.S. well into the first week of the new year.

This is the general setup in play.

The Devil is in the Details
 

We're fairly confident a swath of snow will spread across parts of the Plains to the Midwest in the Friday and Friday night timeframe.

For now, this looks like a modest snow event in these areas.

(MORE: Daily Forecast Maps Next 7 Days)

What happens next along the East Coast this weekend is very much a bold-faced question mark.

Once the sharpening jet's energy pivots over the frontal boundary off the East Coast between the bitter cold air to the north and less cold air to the south, low pressure should develop.

That brings up two possible scenarios this weekend:

If the low intensifies quickly, tracks closer to the Northeast coast: a Northeast snowstorm
If the low doesn't intensify, or does so too far offshore: no Northeast snowstorm

If that wasn't enough, given the cold air's penetation into the Deep South, there's some potential for snow, sleet and freezing rain in parts of the South this New Year's weekend, if the disturbance can tap Gulf of Mexico moisture.

But, again, whether that will happen, much less where, when and how much wintry precipitation actually happens remains highly uncertain.

The bottom line, here, is that you should check back with us at weather.com for the latest forecast changes on what could be an impactful last weekend of 2017.

As we draw closer to the weekend, this rather uncertain forecast will come into focus, allowing us to highlight any specific wintry threats that may impact your New Year's weekend plans.