A powerful storm making its way east from California is threatening major disruptions during the year's busiest travel weekend, as forecasters warned that intensifying snow and ice could thwart millions across the country hoping to get home after Thanksgiving.
The storm has already shut down highways in the western U.S., stranding drivers in California and prompting authorities in Arizona to plead with travelers to wait out the weather before attempting to travel.
The storm is expected to track east through the weekend — into the Plains on Friday, the Midwest by Saturday and the Northeast on Sunday — pummeling a huge portion of the country with snow, ice or flash flooding.
The National Weather Service alerted that travel could become impossible in some places.
The agency issued storm warnings Friday for a swath of the country stretching from Montana to Nebraska to Wisconsin, with heavy snow anticipated in parts of Utah, Colorado, Montana and Wyoming.
One hopeful traveler asked the weather service Friday on Twitter whether it would be advisable to drive to Duluth, Minnesota, over the weekend. The agency warned: "If you are in Duluth by tonight, you will likely be stuck there until at least Sunday afternoon due to heavy snow and blizzard conditions."
The weather threatened to be particularly disruptive on Sunday, when millions of holiday travelers start home. Airlines for America, the airline industry's trade group, expects 3.1 million passengers during what could be the busiest day ever recorded for American air travel.
The group estimated a record of 31.6 million people will travel over a 12-day holiday period. Airlines on Friday said they were so far operating as usual as they monitor the weather. American Airlines issued weather-related waivers Friday for just one airport: Rapid City, South Dakota.
Sections of the state were under a blizzard warning and could see howling winds and as much as 2 feet of snow. The South Dakota Highway Patrol posted a photo on Facebook of a semi-truck that veered from Interstate 90 near Rapid City. "Do not travel if you don't have to!" the agency wrote.
Karlee Wilkinson, a 22-year-old college student in Long Beach, California, missed a Thanksgiving gathering entirely because of snow on the way to her destination.
She and her roommate left late Thursday morning for what was supposed to be a two-hour drive. But the snow started falling in flakes bigger than she'd ever seen, the highway became gridlocked, and their car kept overheating.
At first it seemed like an adventure: They made snowmen in the highway median. But when the sun set, the temperature dropped, and they decided to turn around and head home. Their Thanksgiving dinner was chicken nuggets from a fast food drive-through.
"This is not how this is supposed to go, this is not what an American Thanksgiving is supposed to be," Wilkinson said. "It can only get better than this. I'll never have a worse Thanksgiving, knock on wood."
Galofaro reported from Louisville, Kentucky; Stephen Groves in Sioux Falls, South Dakota; John Antczak in Los Angeles and Paul Davenport in Phoenix contributed to this report.