Hawaii was under a state of emergency on Sunday, amid a powerful storm that bought heavy rain, flash flooding, extreme wind and power outages.
And portions of the mid-South readied for late-day thunderstorms.
Forecasters said the storms would spread eastward by Monday, with mid-Atlantic states and Washington, DC, at greatest risk for high winds and tornadoes.
Successive punches of snow, wind and severe weather were set to impact the eastern half of the United States, said AccuWeather senior meteorologist Tyler Roys.
Beyond the threat to lives and property, "whether it's wind gusts from a squall line, blizzard or snow, or just wind because of the storm, you're looking at several major airports being impacted", Roy said.
An area from central Wisconsin to Michigan's Upper Peninsula was likely to see over 60cm of snow, with higher isolated totals on the peninsula, Roys said.
Lower snow accumulations in places such as Chicago and Milwaukee would likely create trouble for commuters on Monday, he added.
Over 51cm of snow fell in some portions of southeastern Minnesota and western Wisconsin as of Sunday afternoon, according to National Weather Service reports.
Transportation officials warned of worsening conditions with low visibility and snow-covered roadways.
Rain continued falling on Sunday in Hawaii, where hectares of farmland and homes have been flooded, roads have been closed and shelters opened.
PowerOutage.us, which tracks outages nationwide, reported almost 40,000 electric customers in Hawaii without power by midday Sunday.
Flash flooding has been a major problem in recent days in places like Maui, Molokai and the Big Island, where rain had been falling from 2.5-to-five centimetres an hour overnight, according to the Hawaii Emergency Management Agency.
Some areas of Maui received more than 51cm of rain, Maui County Mayor Richard Bissen said in a social media post late Saturday.
"We're seeing flooding, landslides, sinkholes, debris and downed power lines across the county," he said.
More than 210,000 utility customers in six Great Lakes states were without electricity as of Sunday afternoon, according to PowerOutage.us. Some originated on Friday when gusts in the region reached 85 mph (137 km).
The weather service issued a high-wind warning for most of Nebraska, with gusts of up to 97km/h possible amid falling snow. Roys said high winds would affect a region stretching from the US-Mexico border to the Great Lakes, and from Denver eastward to the Appalachian Mountains.
The weather service warned a line of severe storms with damaging winds would cross much of the Eastern US by late on Monday.
