Coldest Air of Season Possible Next Week for Midwest, Northeast

Linda Lam
Published: December 7,2016
The first arctic blast of the season is plunging across the United States, but next week a second round of even colder air may impact the country.
After a record warm fall, winter temperatures are finally appearing across the contiguous U.S., and it appears winter is here to stay, at least through mid-December.
(MORE: December Temperature Outlook)
Here's what we expect from both rounds of cold air.

First Round Into This Weekend

Many locations in the northern Rockies have seen their first subzero temperatures of the season this week, and now this cold is spreading south and east, courtesy of a southward dip in the jet stream.

Current Temperatures

Temperatures will be up to 30 degrees colder than average for much of the Lower 48 at times this week. The colder temperatures will reach the East Coast by Saturday, but conditions will not be as cold for the East as for the Rockies and Plains.
Here is a breakdown of the timing and how cold it is expected to be:

• Below-average temperatures will prevail from the Rockies through the Plains and into much of the Mississippi Valley on Thursday.
• High temperatures will only reach the single digits and low temperatures will be below zero in portions of the northern Plains through this weekend.
• By Friday morning, temperatures will drop into the 20s for much of the South and interior Northeast, and by Saturday morning, lows near freezing are expected in northern Florida.
• The South will see high temperatures in the 50s and 60s replaced with highs in the 30s and 40s.

(FORECAST: Great Falls, Montana | Kansas City, Missouri | Atlanta)

Forecast Morning Lows

Forecast model guidance is suggesting that parts of all 50 states will be below freezing Saturday morning.
(MORE: 5 Things to Know About Cold Fronts and the Plummeting Temperatures They Produce)
When the wind is factored in, it will feel even colder. Wind chill advisories have been issued for parts of the Rockies and Plains, with wind chills as low as 30 degrees below zero possible.
Even though temperatures will be quite chilly, no widespread record lows are expected with this round of arctic air.
(MORE: When Is the Coldest Time of Year?)

Next Week's Arctic Blast

Most areas will see temperatures moderate early next week, with the exception of the northern Rockies and northern Plains, which will continue to experience below-average temperatures. However, this reprieve will not last long, as an arctic cold front will push through the Midwest by midweek. High pressure will then build in behind the front, allowing very cold air to infiltrate portions of the U.S.
(MAPS: 10-Day Forecast)

Next Week's Setup

It does appear that the stratospheric polar vortex is playing a role in the upcoming frigid conditions. The polar vortex is basically a closed circulation surrounding the polar regions in the upper atmosphere, and when it becomes weakened or elongated, a piece of it can surge farther south. The result is arctic cold reaching into parts of Canada.

The details will likely change as we get closer to next week, but here is an overview of what to expect with the next blast of very cold temperatures:

• Temperatures 20 to 35 degrees colder than average are expected in parts of the northern Rockies, northern Plains and upper Mississippi Valley.
• On Wednesday, temperatures 15 to 30 degrees below average will be felt from the northern and central Plains into the Midwest.
• Late next week, very cold conditions will likely spread into the East and possibly portions of the South.
• Highs may only reach single digits for much of the upper Midwest, including Chicago.
• Subzero lows are expected in the northern Plains and upper Midwest, while lows in the single digits and teens will likely be found through the central Plains into the Midwest and interior Northeast.
• Temperatures may not reach the freezing mark late next week from Boston to Philadelphia.

(FORECAST: Bismarck, North Dakota | Chicago | New York)

Forecast Highs

There is some uncertainty in the details, including how cold it will be and how far south the bitter cold will reach. In areas where snow accumulates into early next week, temperatures have the potential to be colder than currently anticipated. Wind chills will be even colder, and a few record cold temperatures cannot be ruled out.
(MORE: Coldest Temperatures Recorded in All 50 States)
Check back to weather.com for updates on the expected frigid temperatures.
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