Massive Winter Storm to Hit the U.S., Bringing Blizzards and Tornadoes

(CNN) - A large winter storm slammed into the western US over the weekend, blanketing mountain areas with heavy snow, and is now set to traverse the nation, threatening dangerous blizzard conditions, strong tornadoes, and flooding this week.

“This winter storm is a true coast-to-coast, top-to-bottom impact that will be felt by every person in the country at some point this week,” CNN Meteorologist Brandon Miller said.

The storm already brought avalanche warnings to parts of the West, shutting down major highways as conditions became icy.

Almost 15 million people in over a dozen states are under some level of winter weather alert as the powerful storm moves across the county, bringing with it a multiday severe storm threat.

The storm will strengthen as it travels eastward, bringing snow to the Rockies tonight, where a foot of snow is expected before the system strengthens even more.

The Upper Midwest, and northern and central Plains will get hit the hardest Monday night into Tuesday as widespread heavy snow falls.

Meanwhile, a widespread area from eastern Wyoming and Colorado to western South Dakota and Nebraska will also have winds gusts as high as 60 mph. Heavy snowfall and strong winds will set the stage for a blizzard, leading to whiteout conditions and impossible travel.

Blizzard conditions are when there are sustained winds of 35 mph or higher and visibility below a quarter mile for at least three consecutive hours.

Winter storm alerts stretch from the Canadian border to the Mexican border and blizzard warnings extend from just west of Denver into the Dakotas.

Some locales inside the blizzard warning areas could pick up as much as 20 inches of snow. The winds could be strong enough to knock down tree limbs and cause power outages, and the harsh conditions could be deadly for anyone outdoors.

Farther east, ice warnings blanket eastern North Dakota, where nearly half an inch of ice could accumulate. If it materializes, power outages are certain and travel will be impossible.

Icing is also possible across southwestern Minnesota and western Iowa, where as much as a tenth of an inch of ice could develop. While the Anchorage school district builds two snow days into the calendar, the system has been closed for four.