Tens of millions of Americans braced Sunday for a massive winter storm that is expected to bring the heaviest snowfall and coldest temperatures in more than a decade to parts of the country.

Kansas, Arkansas, Kentucky and Virginia have declared states of emergency as the polar vortex-driven storm moved east after hitting the central United States. Southern states like Mississippi and Florida also warned of dangerous cold and treacherous conditions, according to the National Weather Service.

A polar vortex is an area of ​​low pressure and cold air that swirls like a wheel around each of the Earth’s two polar regions. Sometimes the Arctic polar vortex wobbles and a lobe flows south, blanketing parts of North America in bitter temperatures.

As the storm moved east, about 60 million people in 30 states from the Plains to the Mid-Atlantic were under weather warnings as a developing low pressure system threatened heavy snow and crippling ice over the next three days.

Travel disruptions

Kansas City International Airport was briefly closed Saturday as crews cleared runways. According to the Associated Press news agency, there were dozens of flights, including a charter jet with the Kansas City Chiefs.

And an 18-mile stretch of Interstate 70 in Kansas was closed as blizzards threatened up to 14 inches of snowfall and wind gusts of 40 mph, with warnings in effect until early Sunday, according to the National Weather Service.

The service is predicting historic precipitation for parts of Kansas and Missouri, predicting over 15 inches of snow from northeast Kansas to northern Missouri – the heaviest snowfall in the region in a decade.

The NWS warned of “significant disruption to daily life,” including “dangerous or impossible driving conditions and widespread closures,” making travel “very difficult to impossible” through Sunday.

Cincinnati, Chicago and St. Louis cleaned up roads and prepared warming centers in advance of the storm.

Scattered snow showers occurred across the northern Plains Saturday afternoon and throughout the evening. More than two million people were under a blizzard warning for most of Kansas and much of Missouri as of Sunday morning, according to the weather service.

Such a warning alerts residents to the likelihood of reduced visibility of 1/4 mile or less and sustained winds of at least 35 miles per hour.

Sunday is expected to bring a severe weather threat across the Lower Mississippi Valley, putting 7 million people at risk of tornadoes causing wind and hail damage in cities like Jackson, Mississippi. and Baton Rouge, Shreveport and Lake Charles, Louisiana.

As the storm moves east, millions more Americans are bracing for record-breaking temperatures, forecasters warn.

Snow will fall across the mid-Atlantic and central Appalachians overnight into Monday morning. These showers will continue into Monday and end Tuesday morning as the system moves offshore.

Washington, D.C., Baltimore and Philadelphia are among major cities bracing for snow and ice Sunday through Monday, with parts of Virginia expecting 5 to 12 inches of snow.

Meanwhile, severe thunderstorms could hit southern states not used to severe cold, including Arkansas, Louisiana and Mississippi.

From coast to coast, there were an estimated nearly 7,000 weather-related flight delays Saturday.

According to FlightAware, Denver International Airport, on the western end of the low-pressure system, led the world in delayed flights, with nearly half of its departures departing late on Saturday.

Major airlines, including American, Delta, Southwest and United, are waiving change fees in advance of likely flight disruptions.

As a result of this system, a significant drop in temperature is expected for the eastern two-thirds of the country. Maximum temperatures will be 10 to 25 degrees below average Sunday through Friday. Highs will be in the single digits and teens in the Plains and Midwest and in the 20s to 30s in the Mid-Atlantic and Northeast.

The most extreme temperatures will be in the northern plains, where overnight lows will fall as low as minus 20 degrees and wind chill values ​​will be around minus 40 degrees. Cold weather warnings are in effect from eastern Montana to Minnesota.