Temperatures to plummet from polar vortex-related Arctic blast

• This event is likely to be far colder and more widespread than the Arctic outbreak that occurred earlier this month.

Threat level: Mother Nature's refrigerator door looks to open, with cold air spilling southward out of northern Canada beginning Friday night and lasting for at least a week.

• Through Sunday, about 81 million people are predicted to see temperatures plunge to below-zero Fahrenheit, and the number affected will increase from there.
• That's a smaller number compared with the polar vortex winter of 2013-2014. But it will increase after Sunday.
• "Dangerously cold wind chills" are likely in the Plains and Upper Midwest, the NWS warns, mentioning the risk of hypothermia and frostbite for people exposed to the cold for too long.

Zoom in: The hazardous cold will be especially disruptive in the South and Southeast, where temperature departures from average will be significant.

• The region also may see a snow and ice storm midweek next week.

The Arctic outbreak is likely to result in a blustery and frigid Inauguration Day, with temperatures in the mid-20s°F and wind chills in the teens on the National Mall when President-elect Trump takes the oath of office.

By the numbers: Here's how some cities may be affected early next week:

• Minneapolis: A high of minus-6°F with a low of minus-14°F on Jan. 20.
• Denver: A high of 7°F and a low of minus-5°F on Jan. 20.
• Dallas: A high of 34°F and a low of 21°F on Jan. 20.
• Washington, D.C.: A high of 26°F and a low of 20°F on Jan. 20.

Between the lines: The factors behind this cold outbreak include a strong high pressure area or "ridge" in the jet stream across the eastern Pacific north to Alaska. Meanwhile, there's a dip, or "trough," in the jet stream across central portions of the U.S.

• This will allow Arctic air to surge southward, Zack Taylor, a forecaster at NOAA's Weather Prediction Center in College Park, Md., told Axios.
• There's also a connection to the tropospheric polar vortex, which is distinct from the higher-level, stratospheric polar vortex.
• The latter feature of the Northern Hemisphere winter climate is currently becoming "stretched" from north to south across the North Pole, but it is not breaking into pieces and surging towards the Lower 48 states as it did in 2014.
• Instead, the stretched vortex is expanding southward and helping to promote the flow of air from northern Canada southward toward the continental U.S., said Judah Cohen, a meteorologist at Atmospheric & Environmental Research.

Zoom out: In the troposphere, at about the same height that jet aircraft cruise, a lobe or multiple pieces of ultra-cold air may enter the U.S. while rotating around Hudson Bay, Canada.

• These could result in some of the most extreme cold temperature anomalies of this event.

• In a sign of the magnitude of the cold air on tap for the U.S., computer models are projecting a record strong area of high pressure over Missouri to form early next week, Taylor said.

Context: Studies suggest polar vortex shifts may be more likely due to human-caused climate change, but this is an area of active research.

• Cohen has published research tying rapid, human-induced Arctic warming to a chain of events including disappearing fall sea ice in the Barents and Kara seas.

Friction point: But this area of climate science is hotly contested, with new studies supporting and knocking it down appearing each year.

The intrigue: While a polar vortex event was much-advertised earlier in January, air temperatures turned out to be milder than anticipated.

• That's not likely to be the case this time, however, Taylor said.
• "The weather pattern just looks so much better than it did compared to a week or so ago," he said, referring to the opportunity for extreme cold.
• He noted wind chills could plunge to minus-30°F to minus-40°F in the Upper Midwest and Plains, and even reach below zero in the Southern Plains, Ohio Valley, Gulf Coast and Mid-Atlantic early next week.
• The cold air is likely to be persistent along the Gulf Coast, Taylor said.

It is not expected that this event will break dozens of records, in part because it can be hard to break cold temperature records at this time of year.

• Also, extreme cold is due to become less severe in a climate that is warming over time due to the burning of fossil fuels.

Go deeper: Abnormally cold weather forecast for Trump's inauguration