The cold air has intruded into the Eastern two-thirds of the country, and it’s going to stick around into the new year. If you thought it was cold now, it will get even worse across most locations. You can blame the Polar Vortex for this cold. Now the Polar Vortex never actually moves around; It sits over the North Pole all year round, but often times the jet stream around the Polar Vortex gets buckled, leading to troughs and ridges. It’s these troughs associated with the vortex that can lead to very significant cold. Therefore, a piece of the Polar Vortex will actually dive southward into the Northeast this weekend. Otherwise, a dominant trough across the East will keep this portion of the nation chilly.
This cold will not be record-breaking for the most part, but we are still expecting up to half a dozen locations each day to break their record low minimum temperatures through at least this weekend.
On Wednesday, the coldest temperatures in terms of greatest departures from normal will be found across the Northern Plains through the Northeast. Departures are forecast to be up to 40 degrees below average. To the south, temperatures will be up to 20 degrees below normal. The only locations east of the Rockies that will remain warm this week is in the Florida Panhandle. Wind chills will make it feel even colder outside with minimum wind chills up to 50 degrees below zero.
Then on Thursday, the chilliest of temperatures will become confined in the Northeast. In this region, high temperatures will be as much as 40 degrees below normal, especially near the Canadian border. Meanwhile, milder air will briefly sneak into western Oklahoma and Texas, but more cold air will return!
The next push of Arctic air will begin to take place on Thursday. Negative temperature anomalies will be the greatest in Montana and the Northern Plains. These areas will experience departures of 20 to 40 degrees from average. It will be more like 20 to 35 degrees below average in the Northeast. For the rest of the Eastern two-thirds of the country, temperatures will generally be 5 to 15 below the average for this time of the year.
That lobe of cold air will push off to the east while expanding as we get into the weekend. The greatest temperature departures will still be in the Northern Plains but also in the Midwest. Again, highs will be as much as 40 degrees below average. Actual temperatures will be brutal with low temperatures up to 30 degrees below zero. Sub-zero temperatures will impact the Northern Plains and the Upper Midwest, but of course the winds will make it feel even colder. Even with just a light wind at 2 mph, it makes all the difference.
New Year’s Eve looks to be the coldest day in terms of departures from normal and the area the cold takes over. In fact, over half of the country in terms of area is forecast to have below freezing temperatures for their high. Even about 20% of the U.S. will only have high temperatures as great as 10 degrees. If you’re going to see the ball drop in Time Square, you better bundle up because actual temperatures will only be in the single-digits but it will feel more like the single-digits below zero.
Now looking ahead to the first weekend of 2018, a pattern change will likely take place. With this change, a trough will dig into the Western half of the U.S. while a ridge of high pressure builds into the East. This ridge will lead to warmer times and above average temperatures east of the Rockies by mid-January. Therefore, your best odds for snow is before the first weekend of January because beyond then, a warm up is likely, thus decreasing your odds for at least significant snow.