PARKS, Ariz. (AP) — A winter storm dumped heavy snow across northern Arizona on Friday, playing a major factor in a more than 15-mile backup on a major interstate. Semi-trucks and other vehicles were stalled on Interstate 40 westbound between Flagstaff and Williams late Friday as the sun set. The standstill dragged on for hours.

PHOENIX (AZFamily) — It’s a First Alert Weather Day as a strong storm system makes its way through Arizona. Expect rain, snow, thunderstorm potential and cooler temperatures to end the work week.