Fire crews with the Coconino National Forest are continuing a 2,700-acre prescribed burn Thursday five miles south of Flagstaff.
The ignitions between Lower Lake Mary and Mountainaire created a large smoke plume visible throughout the area.
The project began Wednesday and officials say firefighters treated 1,700 acres.
The work is expected to continue through Friday and smoke could impact Lake Mary Road, Interstate 40, Walnut Canyon National Monument and the Continental community.
Elsewhere, fire crews continue ignitions on a lightning-caused wildfire near Clints Well and plan other prescribed burns throughout the region in the coming weeks.