CHICAGO - Christmas Day was the second morning Tom and Kristina Waltz and their two daughters awoke at O'Hare International Airport, after days of flight delays and cancellations that marred the holiday travel plans of the Waltzes and countless others.

Elsewhere, deep snow was causing Christmas Day travel problems in the West, where the National Weather Service posted winter storm warnings and advisories for large sections.

The Waltz family, from Vancouver, Wash., tried to fly out of Portland, Ore., on Sunday, but a blast of snow and ice prevented them from catching a flight for two days.

They finally reached Chicago but were stuck spending two nights at a hotel inside O'Hare, unlike others who had to sleep on floors and cots in the terminal. They were eager for their flight yesterday evening to Miami, where they planned to board a Caribbean cruise tomorrow.

"We are checked in" for the flight, Kristina Waltz, a teacher, said yesterday morning. "We'll go into the airport, have some lunch, and play cards some more."

In southwest Colorado, meanwhile, a blizzard warning for the San Juan mountains warned that as much as 3 feet of snow was possible.

In California's Sierra Nevada, heavy snow and whiteout conditions led police to shut down an 80-mile stretch of I-80 for several hours on Christmas between the California-Nevada line and Applegate, Calif. The state Highway Patrol cautioned drivers to be prepared for slow going.

About 2 feet of snow fell overnight in the mountains around Lake Tahoe, bringing totals at some resorts in the last two weeks to 10 feet.

"The powder is so deep, skiers need windshield wipers on their goggles as they come down the mountain," said Kent Hoopingarner, the general manager at Homewood Mountain Resort.

"This is one of the snowiest Christmas holiday periods I can remember," he said.

In the Northwest, hammered by storms over the last week, the weight of snow, ice and water collapsed the roof of Capitol High School early yesterday in Olympia, Wash. Assistant Fire Chief Greg Wright estimated that more than 2,500 square feet of roof fell into the building. No one was injured.

Nationwide, at least 30 people were killed Tuesday and Wednesday in crashes on rain- and ice-slickened roads, many in the country's midsection.

Nearly a dozen flights were canceled yesterday at O'Hare, but no delays were reported. Chicago's Midway International Airport had no delays or cancellations, according to the aviation department.

On Wednesday, more than 100 flights were canceled at O'Hare, the nation's second-busiest airport, as airports across the country recovered from winter storms.

On Christmas Eve, one American Airlines plane left a gate at O'Hare but hit an icy patch while turning onto a runway and slid sideways into the grass. There were no injuries, but the 54 passengers had to be put on other flights.

Slick roads Tuesday and Wednesday were blamed for seven deaths in Wisconsin; five in Ohio; four each in Indiana, Kentucky and Missouri; two in Kansas; and one apiece in Oklahoma, Iowa, Massachusetts and West Virginia. An avalanche killed two snowmobilers in northern Utah.