New Year's travelers jammed the Denver airport Thursday, trying to get out of town ahead of a snowstorm that threatened to close runways and gum up the nation's busy holiday travel season for the second time in a week.

The storm was expected to dump up to 18 inches of snow on the Denver area overnight and prompted Gov. Bill Owens to again declare a statewide disaster emergency, just a week after a pre-Christmas blizzard shut the airport for more than two days. The shutdown stranded 4,700 holiday travelers and backed up flights around the country.

The broad storm stretched from the Rocky Mountains into the western Plains; winter storm warnings were in effect for parts of Colorado, Wyoming, western Nebraska and Kansas, New Mexico and the Texas Panhandle.

Managers at the nation's fifth-busiest airport drew up snowplowing plans, and airlines urged ticket-holders to flee Denver early or delay departures until after the storm. By 2 p.m. United Airlines and Frontier, which together account for 80 percent of traffic at Denver International Airport, canceled more than 180 flights.

Mill and Ann Younkers arrived hours early to check in for an evening Frontier flight back home to Naples, Fla. The couple's trip to see their daughter in Denver was delayed three days by the first storm, and they did not arrive until Christmas morning.

Mill Younkers said he was holding a backup reservation for Sunday and was ready to reclaim his rental car if needed.

"You just have to have a good sense of humor and keep your patience," he said. "Try to always have a Plan B."

The airport and airlines called in extra workers, and security lines moved relatively quickly. But long lines formed at ticket counters as travelers tried to adjust their plans. The Frontier line snaked across the cavernous terminal and wrapped around behind the lines of other airlines on the other side of the building.

Frontier waived its usual change fee to encourage passengers to catch earlier flights. "Let's try and get as many people out ahead of the storm as we can," Frontier spokesman Joe Hodas said.

Some travelers made frantic arrangements to salvage their plans.

Ray Szalay, who missed his flight home to Cleveland after getting stuck in traffic on Interstate 70, grabbed his best chance — a ticket for Houston, where he hoped to find a connecting flight.

After running out of bedding for stranded passengers during the first storm, airport managers lined up cots and blankets and urged food vendors to ensure they had plenty of supplies on hand.

In Denver, plows drenched streets with deicer, offices closed early and residents stocked up on groceries in preparation for the storm.

Ace Hardware in Longmont sold 260 snow shovels — its entire stock — in the first three hours it was open Thursday, cashier Ryan Goforth said.

Federal courts closed early, as did many government offices and businesses in Denver and other cities in the state's main population corridor along the Rocky Mountain Front Range.

Residents of Cheyenne, Wyo., also braced for the second snowstorm to hit the area in a week. Heavy snow began falling around dusk, and forecasters said up to a foot was expected.

In California, another powerful winter storm left tens of thousands of people without power on Thursday as winds gusted to near-hurricane force and blowing snow closed a stretch of Interstate 5 in the mountains north of Los Angeles for 11 hours. It reopened Thursday morning.

Forecasters in California warned of dangerous winds, with gusts over 80 mph, through Friday morning in the region's valleys and mountain passes.