At least 3 waves of VERY COLD air coming to the U.S.

[dan_s]

Winter Storm Blair is just the first major winter storm to impact a large part of the U.S.

It's about to get very, very cold for lots of Americans. A series of blasts of polar vortex air from the north will bring subfreezing temperatures as well as ice and snowstorms to 40 US states, affecting more than 250 million people, according to AccuWeather and meteorologists at many other outlets.

The conditions could be the most extreme cold-weather event since 2011, according to AccuWeather, and will last for more than a week as a series of Arctic air systems move through large parts of the country. In addition to the danger the cold weather itself poses, experts predict there could be travel disruptions, damage to homes and buildings and rolling blackouts in parts of the country.

The first temperature dips will begin on Jan. 3 and could continue to mid-January. Here's what you should know about the polar vortex storms.

What's a polar vortex?
Both poles, north and south, have a constant large area of low pressure and cold air that ramps up in the winter, according to the National Weather Service. Sometimes, as is happening this month, the vortex expands, sending a surge of Arctic air southward into the US. It's happened before, most recently in 2019 and in 2014, affecting hundreds of millions of people across the country.

What areas will be affected?
The winter blasts will extend over a wide range that includes the midwest, the east coast and southern states. Forecast maps show below-freezing temperatures extending from the entire eastern part of the country all the way to parts of California and Oregon and as far south as Arizona, Texas and Alabama. For northern states, temperatures could drop to below -20 degrees as early as Jan. 4.

How long will this storm last?
AccuWeather is predicting a series of three outbreaks, the first happening Jan. 3-4, the second on Jan. 7-8 and the third from Jan. 11 to Jan. 12, although more could be coming after that in smaller areas of the country, likely the northeast and midwest as late as Jan. 15-16 if not longer.