Major winter storm threatens much of the U.S. with intense cold, snow and ice

Tens of millions of people were bracing Sunday for a massive winter storm forecast to bring the heaviest snowfall and coldest temperatures in over a decade to parts of the country.

Kansas, Arkansas, Kentucky and Virginia declared states of emergency as the storm, driven by a polar vortex, moved east after it struck 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 Earth’s two polar regions. Sometimes, the Arctic polar vortex wobbles and a lobe surges south, blanketing parts of North America with bitter temperatures.

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As the storm moved east, around 60 million people across 30 states from the Plains to the mid-Atlantic were under weather alerts, with a developing low-pressure system threatening heavy snow and crippling ice over the next three days.

Video circulating on social media Sunday morning showed snow already falling in Shepherdsville and Monroe County, Kentucky.

Travel disruptions

Over 1,200 flights within, into and out of the United States have been delayed and more than 750 had been canceled as of Sunday morning, according to FlightAware.com. The most affected airports include Kansas City International, where almost 190 flights have been canceled, and St. Louis Lambert International Airport, which has had over 190 cancellations.

Chicago O’Hare International Airport had 120 cancellations and over 60 delays. Southwest Airlines accounted for most of the cancellations and delays, with over 230 flights canceled and 250 delayed Sunday morning.

Kansas City International Airport briefly closed Saturday as crews cleared runways — delaying dozens of flights, including a charter jet transporting the Kansas City Chiefs, according to The Associated Press.

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

The weather service predicts historic precipitation for parts of Kansas and Missouri, forecasting over 15 inches of snow from northeastern Kansas into north-central Missouri — the region’s heaviest snow in a decade.

The weather service warned of “considerable disruptions 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 treated roads in advance of the storm and prepared warming centers.

Scattered snow showers developed across the northern Plains on Saturday afternoon and through the evening. More than 2 million people were covered by a blizzard warning for most of Kansas and a large part of Missouri on Sunday morning, according to the weather service.

Such a warning alerts residents to a likelihood of reduced visibility of a quarter-mile or less and sustained winds of at least 35 mph.

Sunday was expected to bring a severe weather risk across the lower Mississippi Valley, putting 7 million people at risk for tornadoes, damaging wind and hail in Jackson, Mississippi, and Baton Rouge, Shreveport and Lake Charles, Louisiana, among other cities.

As the storm advances east, millions more people were bracing for record low temperatures, forecasters warn.

Snow will arrive in the mid-Atlantic and the central Appalachians overnight into Monday morning. The showers will linger through Monday, ending by Tuesday morning as the system moves offshore.

Washington, D.C., Baltimore and Philadelphia were among the major cities preparing for snowy and icy conditions from Sunday into Monday, with parts of Virginia expecting 5 to 12 inches of snow.

Meanwhile, severe thunderstorms could hit Southern states unaccustomed to severe cold, including Arkansas, Louisiana and Mississippi.

From coast to coast Saturday, weather-related flight delays were estimated at almost 7,000.

At the western end of the low-pressure system, Denver International Airport led the globe in delayed flights, with nearly half its departures Saturday leaving late, according to FlightAware.com.

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

In the wake of the system, a significant drop in temperatures is expected for the eastern two-thirds of the country. Highs will drop 10 to 25 degrees below average starting Sunday through Friday. Highs will range from the single digits and the teens across the Plains and the Midwest, to the 20s to 30s in the mid-Atlantic and the Northeast.

The most extreme temperatures will be in the northern Plains, where overnight lows will dip as low as minus 20, with wind chill values around minus 40. Cold weather advisories are in effect from eastern Montana through Minnesota.

Over 40,000 utility customers across Missouri, North Carolina, Kansas, Texas and Oklahoma were without power Sunday morning, according to PowerOutage.US.