DENVER >> Heavy snow and wind shut down highways today in Colorado and Wyoming, closed schools in Nebraska and forced more than 1,000 travelers to sleep overnight in Denver’s airport after hundreds of flights were canceled just as Thanksgiving travel moved into high gear.

The storm was heading to South Dakota, Iowa, Michigan, Minnesota and Wisconsin, while a “bomb cyclone” weather phenomenon began toppling trees, knocking out power and dumping snow as it barreled into California and Oregon — making for a double whammy of early wintry weather.

The National Weather Service in Northern California urged people to wait to travel for the holiday until the weather improves.

At Denver International Airport, about 10 inches of snow mixed with winds that limited visibility prompted the cancellation of about 30 percent of the airport’s average daily 1,600 flights.

The storm dumped nearly 3 feet of snow in parts of northern Colorado and closed long stretches of highways there and in Wyoming. One person was killed, and two others were injured when a tractor-trailer jackknifed and was hit by two other trucks on Interstate 70 near the Colorado ski town of Vail.

The system moved east, allowing the Denver airport to begin returning to normal.

Southwest Airlines canceled about 200 flights. Spokesman Brad Hawkins said it would take “a couple of days” to get stranded passengers on other flights because there are few during the pre-Thanksgiving travel crush. That makes it hard for airlines to rebook passengers.

About 1,100 people spent the night at the airport, including many cadets from the Air Force Academy near Colorado Springs who either missed flights or wanted to get to the airport before road conditions deteriorated, airport spokeswoman Alex Renteria said.

Among them was cadet Sadie Luhman, whose trip to the airport took three hours — twice the normal driving time. She got to the airport at 1 a.m., 10 hours before her scheduled flight to Chicago for Thanksgiving.

“I just wanted to beat the storm. We kind of left in the middle of it so it kind of didn’t work, but we got here,” she told Denver news station KCNC-TV.

Airport workers handed out blankets, diapers, baby formula, toothbrushes and toothpaste to passengers who camped out on floors and in chairs.

Many government offices closed in the Denver area and Cheyenne, Wyoming, along with colleges and schools not already on holiday break. In Nebraska, several school districts canceled classes Wednesday, and the southwestern city of Sidney had received about 8 inches of snow.

It wasn’t a snow day for everybody. Carli Webber cleared snow off her car and braced herself for her commute to a call center near Denver’s Union Station.

“I am not like a lot of people and cannot work from home, so I have no choice but to go,” she said.

Blizzard and wintry weather warnings extended into the Great Lakes states with the storm expected to bring high winds and snow to Michigan, Minnesota and Wisconsin today and a chance of snow over the weekend for parts of New England, said Alex Lamers, a National Weather Service meteorologist.

“That could be a coast-to-coast storm,” he said.

The storm is expected to dump snow on the airport in Minneapolis, where Delta Air Lines is the major carrier, but most is expected to fall overnight when few flights are scheduled.

Delta prepared by filling de-icing tanks, calling in extra flight dispatchers and operations employees, and having some of its 20 in-house meteorologists focus on the Minneapolis forecast.

“The timing is very helpful,” said Erik Snell, a Delta senior vice president who oversees operations. “It gives the airport time to clear the runways, although we’ll have to watch the residual snowfall in the morning.”

The storm system could mean disappointment for fans of the larger-than-life balloons flown at Macy’s Thanksgiving Day Parade in New York.

Organizers were preparing for the possibility of grounding the iconic balloon characters because of 40-50 mph gusts in the forecast. Rules put in place after several people were injured by a balloon years ago require lower altitudes or full removal if sustained winds exceed 23 mph and gusts exceed 34 mph. The decision will be made on parade day.

The second storm developing in the Pacific Ocean was expected to slam the West Coast of the U.S. tonight, bringing snow to the mountains of California and wind and rain along the coasts of California and Oregon.

The bomb cyclone — a rapid drop in air pressure — could bring waves of up to 35 feet, wind gusts of up to 75 mph and heavy snow in the mountains.

Snow shut down Interstate 80 north of Lake Tahoe and west of the Nevada-California line.

Angela Smith said the Oceanfront Lodge, a hotel she manages in Crescent City, in far Northern California, lost power briefly during rain and strong winds. She said the hotel is ready to withstand heavy downpours.

“It’s blowing pretty good outside but because we’re right on the coast, everything was built to ensure the safety of people,” Smith said.

Forecasters warned of “difficult to impossible travel conditions” across much of northern Arizona later this week as that storm dumps about 2 feet of snow. The approaching storm accelerated the annual winter closure of the highway leading to the North Rim of the Grand Canyon by five days.