Dangerous ice storm underway as Arctic air surges south

A long-duration ice storm impacting portions of the Southern Plains and mid-South is expected to last until Wednesday, bringing the potential for tree damage, power outages and dangerous road conditions to several states.

The big picture: As of Monday evening, 3.3 million Americans are under an ice storm warning, with 15.6 million under a winter storm warning, according to the National Weather Service. Many more are under other types of winter weather alerts, such as wind chill advisories.

Frigid air in the Upper Midwest and Great Plains is headed South,...