A bitter blast of arctic air from Canada is expected to bring “life-threatening” cold to parts of the United States 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 impact 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 already fell in parts of Washington and will continue to impact 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 behind a system already crossing the Pacific Northwest on Tuesday, it said.