CNN  — 

Two powerful storms were leaving much of the United States struggling with blackouts, whiteouts and gusty winds on Thanksgiving Day – and the nightmare could continue in some areas into the holiday weekend.

Of special concern is the forecast for Sunday, when millions of holiday travelers head home. There will be a mix of rain and snow through the Midwest and an icy mix in parts of the northeast, with New York City and Boston forecast to have snow, followed by rain.

Excessive speed in icy conditions was considered a factor in a bus accident that injured several people in southern Colorado. The charter bus carrying 48 passengers rolled over, state police said.

More than 1,500 flights in the United States had been delayed by Thursday evening, with more than 70 canceled, according to FlightAware.

The weather pattern promises to stay active, the National Weather Service said.

“Widespread winter weather, flash flood and wind watches, warnings and advisories are currently in effect … across large portions of the nation,” the agency said.

Rain and snowfall were the big story Thursday, with the latter accumulating in the mountains near Los Angeles. The second storm system was bringing the same across the Great Plains into the Ohio Valley region.

Thousands of homes and businesses were without power, mainly in California, Maine, Michigan, Wisconsin and Pennsylvania, according to the utility tracking site

The weather has been so chaotic, 32 states at one point were under some sort of watch, warning or weather advisory. One system pounded Western states with rain and snow, while an East Coast storm dumped snow as its high winds knocked out power.

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Passenger bus rolled over

The bus incident occurred in Huerfano County, according to the Colorado State Patrol.

The vehicle was traveling northbound on Interstate 25 when the driver lost control on the icy road, officials said. The bus rotated clockwise, ran off the right side of the road, rolled halfway over and came to rest on its top.

The driver was charged with careless driving causing bodily injury, the agency said.

Injuries ranged from minor to life-threatening. Authorities did not say how many of the injured were taken to hospitals.

“Excessive speed for the roadway conditions is being considered a factor in the crash,” the state patrol said in a statement.

Millions face a ‘cornucopia of hazards’

The storm in the western US has put more than 20 million people under a winter threat, CNN meteorologist Gene Norman said.

In California’s Grapevine area between Bakersfield and Los Angeles, heavy snow forced officials to close Interstate 5 for part of Thursday morning, but it reopened later in the day.

As the storm system moves toward the East Coast, it could deliver ice Friday to the middle of the country, then mess up travel into the Monday commute, CNN meteorologist Gene Norman said.

“Thanksgiving 2019 will be remembered as a stormy day for many in the West. A cornucopia of hazards will continue to develop eastward across the country through the weekend,” the National Weather Service said.

Winter storm watches, warnings and advisories touch parts of every western state from Arizona to Montana.

In Arizona, the weather service warned of “impossible travel conditions,” with heavy and drifting snow.

Heavy rains will also pose a flash-flooding threat in Southern California through Thanksgiving and in the Southwest by early Friday, the weather service said.

City officials declared a snow emergency Wednesday in Minneapolis and St. Paul, Minnesota.

The storm set November low-pressure records in parts of Oregon and Northern California, the National Weather Service said.

Winds threatened Macy’s parade balloons

The weather threatened – but could not derail – an iconic facet of the Macy’s Thanksgiving Day Parade.

The event’s 16 giant character balloons aren’t supposed to be flown when sustained winds exceed 23 mph and gusts exceed 34 mph, per New York City regulations. The winds got close to that, as gusts of 32 mph were recorded in Central Park.

In the end, officials allowed the balloons to float along the parade route Thursday, with handlers keeping them fairly low to the ground so they would be more manageable.

CNN’s Christina Maxouris, Madeline Scheinost, Amanda Watts, Judson Jones, Holly Yan and Joe Sutton contributed to this report.