The weather shut down a 150-mile stretch of Interstate 80 in Wyoming as well as a portion in neighboring Nebraska.

Denver got about 5 inches of snow from the storm that intensified on Mother’s Day, but the snow mostly accumulated on the greening grass and trees, rather than sticking to roadways. The lingering snow slowed down Monday morning’s commute in the metro area but driving conditions were worse in the mountains, where over a foot fell in some spots.

The snow blanketed much of the Nebraska Panhandle in the western part of the state, where I-80 was closed mostly to keep drivers from the worse conditions in Wyoming.

Powerful thunderstorms also produced tornadoes in Nebraska on Sunday and caused damage in several towns and rural areas in the east of the state. Officials said the storms damaged homes and businesses in or near Sutton, Garland, Cordova and Daykin, and knocked out power to 18,000 utility customers. By Monday morning, over 5,000 customers were still without power in the Omaha area.

Meanwhile, parts of the Midwest, including Illinois, Indiana and Iowa, were hit by strong thunderstorms and hail, which caused some power outages.

Julie Smith, a spokeswoman for Denver International Airport, said crews treated runways in anticipation of dropping temperatures Sunday night.

"At this point we are seeing some delays with our airlines while they are getting their deicing operations up and running, and we do expect the airlines to be fully deicing in the morning," she said. About 25 flights were canceled Monday morning because of the weather.

In the foothills southwest of Denver, two law enforcement vehicles were hit in less than an hour in traffic-related accidents on Sunday.

A Jefferson County sheriff’s deputy helping a driver who slid off the road was injured when his cruiser was hit by a sport utility vehicle that lost control. Then, a state trooper responding to the original crash was injured when a car lost control, crossed the center line and hit his cruiser head on. The driver from the first accident was in the backseat, but wasn’t injured.

"May snow certainly isn’t unheard of here in Colorado, even down in the Denver metro area," said David Barjenbruch, a weather service meteorologist in Boulder. "If we see the total accumulations that we are anticipating from this storm, we are certainly going to see a top 10 May snow event for the Denver metro area."

In the West, high winds at the bottom of the storm sent dust blowing across Arizona and New Mexico, and the Los Angeles area had been under "red flag" fire warnings, with authorities saying blazes could quickly spread out of control under low humidity, gusty winds and dry conditions.

The storm is the result of a low-pressure system moving east colliding with a cold air mass from the north. Spring-like weather was expected to return to the Rockies by Tuesday.