Flagstaff officials say Coconino County Sheriff's deputies on Thursday will be monitoring U.S. Highway 180, the major highway connecting Flagstaff and the Arizona Snowbowl ski area.
Flagstaff police will also help with any traffic delays or issues going into the weekend.
Authorities say roadways will likely be slick and lead to traffic delays and congestion.
Drivers are advised to not park on the side of any road or go hiking into the forest.
In southern Arizona, a four-mile stretch of Interstate 19 south of Tucson has reopened after being closed due to icy conditions. Interstate 10 in southeast Tucson also has reopened.
Snow accumulations include 17 inches in Flagstaff, 7 in Payson, 5.5 in Sedona and 3.5 in Prescott.
The U.S. Forest Service and city tourism officials are advising that people stay in authorized snowplay areas.
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Copyright 2015 The Associated Press modified.