PHOENIX -- Rain records are falling like, well, rain, around Arizona on Friday, the start of a what is expected to be a very wet weekend.
More than an inch of rain has dropped on Sky Harbor Airport, the most in a single day since 1973. The previous mark was a half-inch.
The airport rain gauge hadn't measured any rain since Sept. 9. Rain began falling Thursday night.
The National Weather Service in Phoenix has issued a flood watch, which will be in effect until 11 p.m. Heavy rain has already forced closure of southbound Loop 303 from Peoria Avenue to Camelback Road. Motorists had already been trapped in flooded areas before 7 a.m.
Snow and whiteout conditions were reported on State Route 87 north of Flagstaff. Locations around Flagstaff reported 1 to 4 inches of snow by 7:30 a.m.
Thursday, Yuma broke a 129-year-old single-day mark with more than a third of an inch.
Forecasters said the storm system from the West could last 18 hours.
In Tucson, firefighters were trying to recover a person who was swept away by high water in the Santa Cruz River. Tucson Fire Department officials said they believed the person was dead but the body has yet to be recovered.
In Prescott, city officials said road crews will be ready to plow snow and treat ice if necessary.
Elsewhere in northern Arizona, State Route 67 to the north rim of the Grand Canyon was temporarily closed due to drifting snow and poor visibility.
On Lake Mohave in northwestern Arizona, workers were removing mud, boulders and other debris that closed the access road to Willow Beach in the Lake Mead National Recreation Area.
The state Department of Public Safety advised motorists driving on wet highways to refrain from abrupt steering changes and braking to avoid loss of control. Motorists also were urged to allow extra space between vehicles.
The weather service said rain will gradually diminish Saturday through Sunday, though flowing washes and continued ponding in low-lying areas were possible into Saturday night.
KTAR's Jim Cross and The Associated Press contributed to this article