The National Weather Service in Flagstaff has issued a flash flood warning for Yavapai County.
At 12:45 p.m., Doppler radar showed thunderstorms producing very heavy rain across the southern end of the Tenderfoot Fire burn scar near Yarnell.
Yarnell is expected to see flooding conditions, with rocks, mud, and other loose materials being washed away.
National Weather Service said "life-threatening flash flooding" is likely and that homes on the east side of Yarnell will "likely be inundated or washed out."
Highway 89 is expected to be affected as well.
Residents are advised to move to higher ground.