A major winter storm has blanketed parts of the middle of the US with snow, disrupting traffic and closing some coronavirus testing sites.

The National Weather Service said at least four inches (10cm) of snow was expected across most of an area stretching from central Kansas north-east towards Chicago and southern Michigan.

Parts of south-east Nebraska and western Iowa could get more than three times that much.

The last comparable snowfall in the area occurred in November 2018, when 8.4 inches (21cm) of snow fell.

A winter weather advisory was issued for north-west Indiana, where the weather service forecast up to five inches of snow by the time the storm leaves the area.

The break in the relatively mild winter in northern Illinois may mean the rest of the season could be more active, said weather service meteorologist Matt Friedlein.

“Now, more active does not necessarily mean more snow,” he said. “If we stay on the milder side of things, that could be more rain or more mixed precipitation.”

The city of Chicago warned residents that hazardous conditions are likely to impact commutes and some power outages are possible due to the wet nature of the snow and gusting winds. Officials have dispatched about 280 salt spreaders to clear the city’s main streets.

By late Monday, 120 flights had been cancelled at O’Hare and 48 flights at Midway international airports, with 15-minute delays at both facilities.

Several coronavirus testing sites in Nebraska and Iowa were closed early because of the snow. More than 10 inches (25cm) of snow had already fallen in parts of eastern Nebraska by Monday evening.

National Weather Service meteorologist Taylor Nicolaisen said 10 to 15 inches (up to 38cm) of snow was likely between York, Nebraska, and Des Moines, Iowa, and that it has been at least 15 years since that area received more than a foot of snow in a single storm.

“This is historic snow,” said Mr Nicolaisen, who is based near Omaha, Nebraska.

Many schools and businesses closed on Monday as the storm moved across the region.

Officials urged drivers to stay off the roads during the storm, especially during the heaviest snowfall. Nebraska State Patrol troopers responded to more than 200 weather-related incidents on Monday.