DENVER — Trucks began rolling again across a southern Wyoming artery that had been shuttered for more than 24 hours and officials in Nebraska made plans to move some primary polling locations Monday following a powerful spring storm that brought up to 3 feet of snow to the Rockies and spawned thunderstorms and tornadoes in the Midwest.

Interstate 80, a major east-west truck route, reopened in Wyoming a day after its closure stranded thousands of travelers and truckers. The interstate quickly became crowded with the trucks that had packed rest areas.

Residents in eastern Nebraska were cleaning up from Sunday’s thunderstorms and twisters, which ripped roofs off homes and toppled buildings, but caused no major injuries.

Numerous tornadoes were reported across at least six Nebraska counties. Trained spotters identified 12 to 15 likely tornadoes as the storms moved across the state. Nebraska Secretary of State John Gale said Monday that two polling places for Tuesday’s primary election in Seward County will be relocated because of the damage.

In Colorado, the snow that began falling on Mother’s Day caused some power outages as it weighed down newly greening trees.

Among those affected by the outages was Denver International Airport, where some escalators and elevators temporarily stalled Monday morning. Airport spokeswoman Julie Smith said a backup generator spared the airport any major problems. At least 27 arriving and departing flights were canceled due to the weather, but Smith said there were no major delays. Crews were working overnight to de-ice runways.

The weather appears to be to blame for at least one fatal crash Sunday on U.S. Highway 285 southwest of Denver.

The highway was one of the worst for accidents in the storm. Two law enforcement cruisers were also hit along the road in less than an hour while responding to other crashes.

Spring is normally the wettest time of year in the Rockies. While snowfall is common in the mountains in May, significant snowfall at lower elevations like Denver in May only occurs every five or 10 years, Colorado state climatologist Nolan Doesken said. Denver got between 4 and 7 inches of typical heavy, wet spring snow.

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. While temperatures were expected to drop below freezing Monday night, spring-like weather was expected to return to the Rockies by Tuesday.