By Brendan O'Brien and Gabriella Borter
(Reuters) - Two powerful storms packing heavy snows and strong winds are expected to sweep across the western half of the United States this week just in time to wreak havoc on the plans of millions of Americans traveling for Thursday's Thanksgiving Day holiday.
Heavy snow began falling in Denver on Monday night, with the National Weather Service (NWS) warning motorists of "significant travel delays" from the accumulating snow.
Snowfall is expected to increase over the course of the night to about 2 inches per hour, the NWS said.
A storm will dump more than a foot (30 cm) of snow as wind gusts reach 45 mph (72 kph)in an area from southern Wyoming to central Colorado.
The same storm will then drop 6 to 12 inches (15.2 to 30.5 cm) of snow as it moves east across Nebraska and Kansas and into Minneapolis on Tuesday before reaching the upper Great Lakes by Wednesday, the NWS said.
Most school districts in the Denver metro area, along with state government offices, announced that they would be closed on Tuesday.
A second strong storm is expected to dump heavy snow on parts of the Pacific Northwest starting Tuesday night, with blizzard-like conditions in Oregon and Northern California, the NWS said.
"Everyone say a prayer to the Colorado weather gods that my flight doesn’t get canceled on Wednesday night," Evelyn Graham, a 26-year-old biology student at the California State University in San Marcos, said in a Twitter message. "I wanna go home for Thanksgiving."
Some 55 million travelers will fly or drive at least 50 miles (80 km) from their homes this Thanksgiving, according to the American Automobile Association.
At Denver International Airport, nearly 500 flights scheduled to depart and arrive on Tuesday have been canceled ahead of the storm, airport spokesman Alex Renteria told Reuters.
In the western half of the country, dozens of winter storm watches and warnings were in effect, complicating the plans of many would-be travelers.
Forecasters and transportation officials in several states in the western half of the country were discouraging traveling on roads as blowing snow could cause poor visibility and make driving difficult.
Airlines and airports also warned travelers to check the status of their flight and to consider rescheduling as weather may disrupt service.
Hazardous weather is expected on the East Coast starting late on Wednesday and into Thanksgiving when wind gusts up to 45 mph are possible, the NWS said.
The wind could force the Macy's Thanksgiving Day Parade in New York City to ground its balloons. City guidelines prohibit the giant character balloons from being sent aloft if sustained winds exceed 23 mph and wind gusts top 34 mph, Macy's spokesman Orlando Veras said.
"We monitor the weather on a daily basis, but at this time, it is too early to make any determinations regarding the flight of the Parade's giant balloons," he said.
The guidelines in New York took effect in 1998, a year after high winds whipped the Cat in the Hat balloon into a crowd of parade-watchers, injuring four.
(Reporting by Brendan O'Brien in Chicago and Gabriella Borter in New York City, additional reporting by Keith Coffman in Denver and Subrat Patnaik in Bengaluru; Editing by Matthew Lewis and Gerry Doyle)