Washington DC - Blizzard and winter storm conditions blasted the Midwest early Sunday, as a massive weather system began tracking eastward across the US, with authorities warning of some of the heaviest snowfalls in a decade and severe impact on transport.

Snowfalls of 15 inches or more in some areas "will make travel extremely hazardous, with impassable roads," the National Weather Service (NWS) said in an update early Sunday.

That, combined with accumulations of up to a half-inch of ice in some areas – as well as widespread tree damage from powerful wind gusts – could lead to "prolonged power outages."

The first major storm of 2025 is already disrupting travel.

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A video posted by the Weather Channel showed cars skidding off ice-coated highways in Kansas and tractor-trailers jack-knifing dangerously.

The NWS issued blizzard warnings in Kansas and Missouri, with a belt of winter storm and ice storm warnings stretching all the way to the US capital on the East Coast, putting an unusually broad 1,500-mile swath under immediate threat. American Airlines posted a travel advisory covering 46 airports from Kansas to New Jersey.

But the latest forecast from the NWS suggested the worst was yet to come, with "blizzard conditions" and winds up to 50 mph expected in the state. As the storm accumulates through Monday, "the snow will significantly reduce visibilities," the NWS said.

A band of eight to 14 inches of snow is expected to be dumped from northeast Missouri through the Central Appalachians, it said.

Areas around Washington could see up to 10 inches overnight Sunday into Monday, making "hazardous travel and closings" likely, the Washington Post reported.

That could complicate the task of US lawmakers, who by constitutional mandate must meet on Capitol Hill on January 6 to certify Donald Trump as the winner of last year's presidential election.

"Whether we're in a blizzard or not," House Speaker Mike Johnson said on Fox News Sunday.

"We cannot delay that certification... I hope we have full attendance."

A joint session was set to convene at 1:00 PM.

Nationwide, nearly 70 million people are under some sort of weather alert, according to broadcaster CNN.

With the jet stream diving southward, temperatures are expected to plunge, in some places to below zero degrees Fahrenheit, while strong wind gusts compound the dangers.

The mercury could sink tens of degrees below seasonal norms down to the US Gulf Coast. Before then, severe thunderstorms are expected across the lower Mississippi Valley, the NWS forecast.

Another major concern is freezing rain and sleet. A thick coating of ice could make travel hazardous, bring down trees, and topple electricity lines.

The governors of Kentucky, Missouri, and Virginia have declared a state of emergency in their states, and have taken to social media to warn residents to stay at home.