Another wave of extreme cold weather set to blast south across the U.S.

A bitter Arctic outbreak has swallowed the Lower 48, bringing temperatures 30 to 50 degrees below average and wind chills as low as minus-60 to minus-70 degrees. Major cities such as Chicago and Kansas City struggled for days to make it above zero degrees. At one point, 30 states were under wind chill advisories or warnings. Now, a reinforcing shot of bone-chilling air — just as frigid as the first — is about to plunge south, and temperatures will plummet once again.

Weather models indicate this air mass is from extreme northern Nunavut, Canada, or about the same latitude as northern Greenland. In other words, straight out of the high Arctic. Digits will drop to 40 degrees below seasonable averages.

This week’s Arctic blast pales in comparison to cold of the past

The air mass will stick around into early Sunday before an abrupt and dramatic warm-up allows temperatures to spike. By the start of the workweek, the Great Lakes, Plains and Ohio Valley will be running 10 or more degrees above average. That warmth will be heralded by a quick thaw, which in some cases could cause minor to moderate flooding. The unseasonable mildness will carry through much of the remainder of January.

Arctic high pressure is diving out of British Columbia and Alberta, Canada. It’s high pressure because the cold air is dense, and heavier — therefore making a high-pressure system. It will bring with it clearing skies and dangerously low temperatures, with little in the way of cloud cover to blanket overnight temperatures and trap heat.

Wind chill advisories reach from the Dakotas and the Northwest Angle of Minnesota as far south as Fayetteville, Ark. In many places, a fresh snowpack will help to make the air even colder.

“The dangerously cold wind chills could cause frostbite on exposed skin in as little as 10 minutes,” wrote the National Weather Service in Glasgow, Mont. That’s where wind chills could dip to the minus-35 to minus-40 degree range.

The northern Rockies and Plains will see the cold into Friday; by Saturday, it will reach the Tennessee Valley, Texas and parts of the South. It wanes into Sunday as the Arctic high weakens and shifts east, with clockwise winds on its back side inducing a warming southerly flow over much of the country.

There are three more days of subzero cold over the central United States. On Friday morning, lows of minus-20 to minus-30 degrees will be common in Montana, with negative teens for Wyoming and negative single digits across Nebraska, the Dakotas, Iowa, Minnesota and western Wisconsin. The zero-degree line should make it as far south as Kansas City; the airport already set records Sunday and Monday morning at minus-12 and minus-16 degrees respectively.

It will get even colder Friday night as the Arctic high settles across the nation’s heartland. Kansas City could dip to minus-7. Negative teens will be common across the northern Plains and Upper Midwest, with a few minus-20s along Interstate 29 in eastern South Dakota and Nebraska, as well as in western Iowa. Omaha could make it to minus-18 on Saturday morning, falling just shy of the record of minus-22. Still, the Weather Service is warning folks that the cold could be dangerous to life and property.

“Wrap pipes with insulation and seal windows to avoid loss of heat from your home,” the agency wrote. “Keep a slow steady stream of water running from indoor faucets, and open cabinet doors to allow warm air to circulate around inside pipes.”

By Saturday night into Sunday morning, the negative readings will be relegated to the Corn Belt, though the north-central United States will still be very cold. Lows of minus-15 or colder are likely in eastern Iowa and northwestern Illinois. Saturday night will dip to minus-4 in the Windy City.

The frigid air will also reach the East Coast. Freezing highs — about 10 to 20 degrees below normal — are expected both weekend days from Northern Virginia to Maine, where highs will hover in the teens. Saturday will be slightly colder than Sunday. Wind chills will dip into the single digits as far south as Atlanta and minus-10 to minus-20 in the interior Northeast on Saturday morning.

By Monday, the negatives and single digits largely disappear in the north-central United States, while it will take until Tuesday or Wednesday for temperatures to moderate in the Northeast.

As if by the drop of a hat, a sudden thaw arrives Monday from Montana to Wisconsin. Arctic high pressure will push east, with winds turning southerly and moving warm air northward. Highs in the mid-30s to lower-40s will be common across the Corn Belt and central Plains, though the northern Plains will remain below freezing.

In some pockets, the thaw might contribute to flooding where there’s still a snowpack, especially in northern Kansas and Arkansas. Thereafter, the Weather Service’s Climate Prediction Center suggests a dramatic warm-up, with temperatures up to 30 degrees above average in Minnesota.

Jason Samenow contributed to this report.

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