A blizzard of dust powered by 74 mph wind gusts resulted in zero visibility and forced the closure of an 8-mile section of Interstate 40 west of Winslow for about 12 hours Wednesday.
Conditions were severe over a 30-mile stretch of highway -- four times the usual area affected.
It was the fourth time in a month the interstate was closed because of high winds, dust storms and limited visibility. In that area, the interstate bisects Tucker Flats, a dry lake bed that is the source of the dust.
As the day wore on, the affected area expanded, covering from milepost 230 to milepost 260.
Beginning late Wednesday morning, sustained winds of 50 mph and gusts up to 69 mph stirred up pockets of dust clouds and reduced visibility to near zero.
The changing wind directions, which made for highly variable visibility conditions, and 70 mph wind gusts, which made drivers wrestle with steering wheels, prompted highway and public safety officials to close the interstate at 11 a.m.
As of 11:15 p.m., the Interstate was not expected to reopen until midnight Wednesday night at the earliest.
Highway patrol officers turned around eastbound drivers at Two Guns and diverted westbound I-40 traffic into Winslow.
Semi-truck drivers, meanwhile, parked their rigs bumper-to-bumper along the highway's shoulders as they waited out the dust storm, which gained strength through the late afternoon.
Rod Wigman, public information officer for the Arizona Department of Transportation, monitored conditions from Winslow, where he was stationed most of the day.
He reported "really heavy dust" for a mile or two and then clear spots, which gave drivers a false sense of the difficult driving conditions down the road.
"They'd break out of one of the dust cloud areas and then they'd pick up speed and then hit another dust cloud," Wigman said.
By 6 p.m., an ADOT supervisor on the scene reported that eastbound drivers coming out of Flagstaff were stopping on the interstate instead of turning around and returning to Flagstaff. ADOT crews and DPS officers were working to correct the situation Wednesday evening, Wigman reported.
A stronger-than-usual spring storm moving into Arizona from the Pacific caused the gusty winds.
In Flagstaff, sustained winds throughout the day were about 30 mph, with gusts reaching around 45 mph.
Today, there's a chance of precipitation during the day, with snow levels dipping to 5,500-6,000 feet but only light accumulations of no more than an inch of snow.
"The storm system is going to shift just beyond us, so we'll be left with lighter winds and scattered rain and snow showers and much cooler temperatures on Friday," said Daryl Onton, a meteorologist for the National Weather Service in Bellemont.
However, high winds will continue to buffet the entire Little Colorado River Valley, which includes Winslow, Tuba City, St. John's and Window Rock, today and this evening, as those winds move into east-central Arizona.
Laura Clymer can be reached at firstname.lastname@example.org or 913-8601.