Los Angeles, Feb 23 (IANS): More than 65 million people across 29 US states are under winter weather alerts that include warnings of severe icing and extreme coldness.

A massive winter storm is expected to bring heavy snow and a torrent of rain to most of the northern US this week, with "extreme impacts" felt across a wide swath of the country, CBS News reported on Wednesday.

The upper-level pattern will intensify in the coming days as millions of Americans, from the Pacific Northwest to the Northeast, brace for oncoming snow, frozen rain, strong winds and potential flash flooding.

The extreme weather is likely to make travel dangerous and lead to power outage in many regions, Xinhua news agency reported.

California is bracing for several feet of snow expected in the mountains with a few inches possible in lower elevations, according to the US National Weather Service in Los Angeles.

"Now is the time to prepare for a cold and dangerous winter storm expected for much of the week," the weather service in Los Angeles tweeted.

"Gusty and potentially damaging winds are also expected."

More than 1,400 flights scheduled for Wednesday within the US have been cancelled, mostly in Minneapolis, Denver and Detroit, CNN reported, citing the tracking site FlightAware.