LONGMONT, Colo. — A powerful late-autumn storm dumped up to 24 inches of snow in the Colorado mountains on Tuesday before barreling onto the plains, prompting airlines to cancel about 500 flights at the Denver airport and leaving hundreds of miles of highways slippery with snow and ice.

The snow tapered off Tuesday afternoon as the storm moved northeast, leaving behind drifts up to four feet high.

“It’s going to be western Nebraska’s turn next,” National Weather Service meteorologist Todd Dankers said. “It’s going to end up eventually in Minnesota.”

It was the first big storm of the season for most of Colorado and Utah. Schools closed in some towns in at least four states.

Some flights at Denver International Airport were more than four hours late after at least seven inches of snow fell there, airport officials said.

More than 600 miles of Colorado Interstate highways were snowpacked or icy, and gusts as strong as 58 mph left near-whiteout conditions in isolated areas of Colorado’s eastern plains, Dankers said. Few highways were closed, however.

A snowplow slipped off a highway in the foothills west of Boulder early Tuesday and landed up-side-down in a creek, but the driver wasn’t injured.

The accident happened at about 4:30 a.m. in Boulder Canyon, said Amy Ford, a spokeswoman for the state Department of Transportation. Nothing spilled from the truck into the creek, she said. The cause of the accident was under investigation.

The wind piled up drifts three to four feet deep in the small northeastern Colorado town of Merino. Schools and the town offices were closed but some businesses opened as usual.

“I think we’re just more used to it,” said Jada Gettman, owner of Grandpa’s restaurant in Merino, which was open. “The snowing and blowing doesn’t affect us as much.”

About 24 inches of snow fell in the west-central mountains near McClure Pass, the National Weather Service said.

The town of Larkspur, in the foothills north of Colorado Springs, reported 17 inches of snow, and cities along the north-south Interstate 25 corridor reported up to a foot. Farther east, the Colorado plains received four to eight inches of snow.