A winter storm dumped heavy snow across northern Arizona on Friday, playing a major factor in a more than 15-mile (24-kilometer) backup on a major interstate. Semitrucks and other vehicles were stalled on Interstate 40 westbound between Flagstaff and Williams late Friday as the sun set.

There are three rounds of rain and snow in the forecast this week for Arizona. The most impactful round is expected on Thursday, with rain, snow and gusty winds expected.