BISMARCK, N.D. — Harsh cold descend on the nation’s midsection Monday as a polar vortex gripped the Rockies and Northern Plains on the heels of weekend storms that pummeled the eastern U.S. with floods, killing at least 13 people.

The National Weather Service warned of “life-threatening cold” as wind chills dropped to minus 60 degrees Fahrenheit in parts of North Dakota on Monday and minus 50 degrees Fahrenheit in parts of Montana. Today’s morning was forecast to be even colder.

Extreme cold warnings were issued for an 11-state swath of the U.S. stretching from the Canadian border to Oklahoma and central Texas, where the Arctic front was expected to bring near-record cold temperatures and wind chills in the single digits by midweek.

Meteorologists had predicted that parts of the U.S. would experience the 10th and coldest polar vortex event this season. Weather forces in the Arctic are pushing chilly air that usually stays near the North Pole into the U.S. and Europe.

– The Associated Press