A bitter blast of arctic air from Canada is expected to bring "life-threatening" cold to parts of the U.S. in the lead-up to Christmas, weather officials have warned.
A strong arctic high-pressure system extending from western Canada to the northern Plains is expected to bring "very cold air" across the region while extending into parts of the Pacific Northwest this week, the National Weather Service said. As of Tuesday afternoon, 48 million people were under winter alerts from the Northwest to the Appalachians. In more than 20 states, 42 million were under wind chill and freeze alerts.
Along with the bitter cold, snow is also expected to affect parts of the U.S., bringing "pre-holiday travel headaches," it warned.
As the cold air mass bites deeper into Washington, "an approaching storm system and surge of moisture will lead to widespread snow to impact northern and western portions of The Evergreen State," the weather service said. More than a foot of snow has already fallen in parts of Washington, and it will continue to affect the Cascades and northern Rockies through Tuesday evening.
The heaviest snowfall amounts are expected in the higher terrain of the Cascades and into northern Idaho, northwest Montana and western Wyoming, the weather service said, adding: "These regions will have the best chances for over a foot of snow."
The dangerous arctic air over the northern Plains and western Canada is expected to move south, following a system that was already crossing the Pacific Northwest on Tuesday, it said.
Cold weather, combined with wind gusts of up to 60 mph, could bring "life-threatening" wind chill values as low as minus-40 degrees to parts of the central and north-central U.S., the weather service said.
"This level of cold can be life threatening and lead to frostbite on exposed skin in as little as 10 minutes," it said.
Wind chill warnings and watches have been issued across 17 states from Washington to Texas.
Snow is also expected to add to "pre-holiday travel headaches" from the central Plains to the Midwest and the Great Lakes as a major storm begins to brew, the weather service warned.
"Areas of light to moderate snow are likely along and behind the cold front as it impacts central Plains and Upper Mississippi Valley on Wednesday and Thursday," it said.
In addition to the snow, strong winds are also expected to hit "nearly the entire eastern half of the U.S. as this large system becomes fully mature by Thursday night," the weather service said.
Major airport hubs in Chicago; Detroit; Cincinnati; Charlotte, North Carolina; Washington, D.C.; New York; and Boston are expected to be affected by the storm, with possible flight delays or cancellations. Severe turbulence is also possible.
More than a half-million flights are expected to take off between the end of the year and early January, the Federal Aviation Administration said. AAA said it believes driving will be the most common form of travel, with nearly 102 million people packing up their vehicles and hitting the roads. Nearly 7.2 million are expected to fly, it said.
Heavy winds are expected to create blizzard conditions throughout the central and the northeastern Plains, the Upper Midwest and the Great Lakes. Lake Michigan could get waves as high as 15 to 20 feet, with 50 to 60 mph winds blowing the freezing spray inland. That could lead to homes’ being encased in ice, similar to what happened on Lake Erie in 2020.
Meanwhile, low visibility is expected to further imperil travel on top of snow-covered roadways.
The weather service warned of the possibility of power outages from the Midwest to the Northeast.
"With such a large and powerful storm system impacting a majority of the nation during one of the biggest travel weeks of the year, it is imperative that travelers check the latest forecast before venturing out," it said.