Tens of millions of people across the central and southern US are at risk Tuesday of severe thunderstorms and tornadoes and fire weather on the storm’s warm side and blizzard conditions on its cold side.

Blizzard conditions in parts of southern Minnesota made travel there dangerous Wednesday morning, the weather service office in the Twin Cities warned on social media. Heavy snow and strong northerly winds slowed travel across much of the Twin Cities, southern Minnesota and western Wisconsin, the weather service said.

The winter storm could impact up to 170 million people across more than 20 states from the southern Plains to the Midwest and East, AccuWeather said.