DENVER - Fog, wind and drifting snow made travel difficult on the Colorado plains today as a potent spring storm plodded eastward into Kansas, Oklahoma and Texas.

The storm dumped up to 17 inches of snow in the Denver area Thursday, and airlines canceled at least 475 flights at Denver International Airport.

Between 300 and 400 stranded travelers spent Thursday night at airport, but flights were returning to normal this morning, airport spokesman Chuck Cannon said.

Southwest Airlines said its was operating on a regular schedule. Denver's two biggest carriers, United and Frontier, didn't immediately return calls.

The National Weather Service said fog was blanketing parts of eastern Colorado, where 20 mph winds pushed snow into drifts of up to 5 feet deep.

A blizzard warning remained in effect for much of southeastern Colorado, including Pueblo, where winds were clocked at 43 mph.

The wind was strongest near the Colorado-Kansas border, said Randy Gray of the National Weather Service in Pueblo.