US is about to have a 'once in a generation' winter storm with 'life threatening' conditions experts say

A major storm is set to hit the US, with experts warning that it could be 'life threatening'.

People are being urged to take proper precautions, with powerful winds set to sweep across the North East of the country later this week, affecting millions.

The storm, which has been branded a 'once-in-a-generation' event by experts, began in the Pacific Northwest yesterday (20 December) and had made its way through the Rockies as of this morning (21 December).

Currently, over 90 million people are under winter weather alerts, while a further 87 million are under wind chill alerts.

And it's predicted that the storm will become something called a 'bomb cyclone' by the end of the week.

This is where a storm appears to gather momentum and intensifies rapidly as the air pressure drops drastically.

In a post to its Twitter account, the National Weather Service's Buffalo station warned of potential widespread power outages over the coming days.

It said: "A once-in-a-generation storm will produce high winds east of Lake Ontario Thursday night into Friday morning, then over a larger coverage of our region Friday into Saturday.

"Winds could gust over 65 mph, leading to at LEAST scattered power outages, if not widespread outages."

Already there has been huge disruptions to people's travel arrangements in the week running up to Christmas.

Major airlines like United, American and Delta have offered waivers to travellers who want to reschedule their flights.

And flights in Vancouver and Seattle were cancelled yesterday.

The National Weather Service said it believes the storm will reach the pressure equivalent of a Category 3 hurricane as it moves eastwards.

And it warned that 'dangerous cold' and 'sudden whiteouts' should be expected.

It said: "Considerable travel impacts behind an Arctic cold front this week. Brief bursts of heavy snow, strong wind gusts, and rapidly falling temperatures will likely lead to sudden whiteouts, flash freezing, and icy roads.

"Even in areas unaffected by snow, dangerous cold is expected.

"This is a case in which snow totals may not tell the whole story. Even small snow amounts, when combined with very strong wind gusts and plummeting temperatures, can cause poor visibility and slick spots on roads.

"The sudden arrival of these conditions can increase the danger."

In Chicago, where it's feared residents could experience blizzard conditions tomorrow (22 December), the windchill is predicted to reach 30 degrees below zero by the end of the week.

However, even those places that manage to escape the snow won't be free from the cold, with temperatures to be 40 degrees lower than normal for some areas, experts warned.