As Thanksgiving travelers return home Sunday, two powerful storms on each side of the country have left about 50 million under some kind of winter weather alert.

Airlines have delayed flights across the country on what is expected to be the busiest travel day in the US. American, Delta and other airlines issued travel waivers for those who want to cancel or change their plans.

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A winter storm that has pounded the Upper Midwest with heavy snow is shifting over to the Northeast, where it will dump more snow mixed with freezing rain, the National Weather Service said.

Blizzard-like conditions will finish off the holiday weekend in the Great Lakes region, the weather service said, while up to 12 inches of snow may cover parts of the Dakotas to Michigan, it said.

By Tuesday, parts of the Northeast will see up to a foot of snow, the service said. New York will see up to 2 inches of snowfall each hour on Sunday and Monday, it said, making for dangerous roads as the snow piles on. Downed trees and power lines are also possible.

Meanwhile, rain will stretch from coastal areas in the Northeast to farther south where it will be accompanied by thunderstorms and strong wind gusts, the weather service said.

"A cold front will be positioned from central Ohio, arcing eastward near the Appalachians, then south-southwestward into the Florida Panhandle," it said. Thunderstorms are possible along that front, it said.

Rain and wind in California

Across the country, a storm in the West Coast will continue to drench California through Monday, while parts of the state in higher elevations will see snow.

"Some flooding is possible in parts of Northern California, especially for areas with burn scars," the weather service said. "Meanwhile, the Sierra Nevada could see snow measured in feet."

In parts of Southern California, about 10,000 customers were in the dark, Southern California Edison said. The utility said the outage was storm-related, after winds and snow topped trees downed wires.

"No Wi-Fi, no electricity, so it's like we're back in the 1800s," Fabrice Vignati who was in Crestline --- a little more than 70 miles east of Los Angeles -- told CNN affiliate KTLA.

The company said it would be passing out firewood to affected residents with the help of authorities.

The storm will linger over the state through Tuesday, the weather service said.

Sunday, expected to be a historically busy day for US airlines, will see an anticipated 3.1 million passengers, according to Airlines for America, an airline trade organization. A record 31.6 million passengers were forecast to travel on US airlines during the Thanksgiving holiday period, up 3.7% from last year.

But by early Sunday morning, more than 150 flights had been delayed, according to FlightAware.com. Travel impacts are expected to last through Monday, the weather service said.

Delta Airlines announced weather waivers for 16 cities in the Upper Midwest on Saturday, and 22 cities in the Northeast for Sunday and Monday, including airports in Boston and the New York area.

American Airlines issued waivers for passengers traveling Sunday and Monday on flights to and from New York's John F. Kennedy and LaGuardia airports as well as Newark and the airline's hub in Philadelphia. Other cities in the American Airlines announcement include Boston, Buffalo, Pittsburgh and Toronto, Canada.

Powerful storm pushes into Midwest with heavy snow and winds

Powerful storm pushes into Midwest with heavy snow and winds

Powerful storm pushes into Midwest with heavy snow and winds

Powerful storm pushes into Midwest with heavy snow and winds

Powerful storm pushes into Midwest with heavy snow and winds

Powerful storm pushes into Midwest with heavy snow and winds

Powerful storm pushes into Midwest with heavy snow and winds

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CNN's Faith Karimi and Dakin Andone contributed to this report.