Washington, Dec 22 (IANS): A powerful "once-in-a-generation" winter storm in the US that has brought with it crippling snow and freezing temperatures, may disrupt travel for many during the upcoming holiday season.

The Arctic winter storm began in the Pacific Northwest on Tuesday, and has made its way east through the Rockies as of Wednesday morning, reports the BBC.

It is then expected to hit the Great Lakes later this week, and will become a "bomb cyclone" by early Friday.

Major US airlines like United, American, Delta and Southwest have issued fee waivers to travellers who wish to reschedule their flights in anticipation of the big storm.

More than 70 million people from Washington state to Maryland are also under a winter weather alert, as well as parts of Canada.

In Vancouver and Seattle, flights were cancelled on Tuesday as the storm began to hit the region.

As it moves east, the storm is anticipated to dump heavy snow into major midwestern airports in Detroit and Chicago by Thursday.

It is also expected to cause widespread power outages in the area.

The National Weather Service in Brooklyn, New York has called it a "once-in-a-generation" winter weather event, especially as the storm reaches the Great Lakes region, where its pressure is expected to reach the equivalent of a Category 3 hurricane.

Chicago's National Weather Service branch has warned of a "significant threat to life for anyone stranded in the storm", as the wind speed is expected to be greater than 88.5 kph.

The storm will also bring life-threatening frigid temperatures, with every state in the continental US could see the mercury dip below -6 degrees Celsius on Christmas Eve, the National Weather Service said.