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 Fahrenheit in parts of North Dakota on Monday and minus 50 F in parts of Montana. Tuesday 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 death toll in flood-battered Kentucky rose to 11, Gov. Andy Beshear said Monday. Nine the deaths were flood-related. Two fatal vehicle crashes were connected to the severe weather, he said, and at least 1,000 people stranded by floods had to be rescued.

Parts of Kentucky and Tennessee received up to 6 inches of rain as severe storms swept across the South. Water submerged cars and buildings in Kentucky and mudslides blocked roads in Virginia.

West Virginia had one confirmed flood-related fatality with several people still missing, Gov. Patrick Morrisey said Monday. At least 13 counties were under a state of emergency and some areas were cut off to vehicle traffic.

In Atlanta, a person was killed when a large tree fell on a home early Sunday.

Flood warnings were extended Monday across most of Kentucky and portions of Arkansas, Tennessee, Mississippi, Alabama, West Virginia, Virginia and Ohio.

In Nebraska, where much of the state was under a winter weather advisory, a state trooper was killed Monday morning while responding to a crash on Interstate 80 near the town of Greenwood. The trooper’s name and further circumstances of the fatality were not immediately released.

Ice and snow made travel treacherous in large swaths of Michigan, which remained under a winter weather advisory until Monday afternoon.

Authorities in Colorado reported eight people were killed in fatal vehicle crashes since Valentine’s Day and warned drivers to be cautious.

Avalanche warnings were issued for numerous areas of the Rocky Mountains, with the danger rated high in portions of Colorado, Utah, Idaho and Wyoming.

The Mount Washington Avalanche Center issued an avalanche warning Monday for areas of the White Mountains in New Hampshire. Two ice climbers were rescued in the White Mountains on Sunday after triggering an avalanche that partially buried one of them, officials said.

Parts of a southwest Detroit neighborhood were submerged after a nearly century-old water main burst Monday, flooding streets, sidewalks and yards under several feet of water.

Firefighters used a ladder to help one person from the roof of a car in waist-deep water and a bulldozer was used to navigate a flooded street and help people leave a home, according to the fire department.

The 54-inch transmission main was built in 1930, according to the Great Lakes Water Authority.

Crews were attempting to isolate the break. It was not clear what caused it, but overnight temperatures had been well below freezing.

No injuries have been reported. Mayor Mike Duggan says people affected by the flooding can shelter in place if they have power and feel safe. Those who want to leave can call 911 and fire crews will help them from their homes and take them to a temporary shelter.