Relentless spring winds in the northern Arizona high desert are part of the local experience; an accepted, if grudgingly tolerated, thread of the high desert tapestry.
But high winds stirring up dense, impenetrable dust storms that effectively blind drivers for brief seconds or long, white-knuckled minutes create dangerous driving conditions that area agencies are hard pressed to prevent.
Captain Larry Parks, District 3 commander for the Arizona Department of Public Safety, said the dangerous dust storms of the past three years, and unprecedented multiple interstate closures during the spring of 2009 and 2010, have officials looking hard at the causes and potential remedies to the situation.
Parks reported that DPS, the Arizona Department of Transportation (ADOT) and the National Weather Service were among the agencies represented at a meeting in Flagstaff following the severe wind season of 2010, which saw stretches of Interstate 40 around Holbrook and Winslow closed a record seven times because of high winds and dust.
The sole agenda item for the meeting was determining what has been causing the increase in dusty, windy conditions and what, if anything, could be done to help the situation.
The ongoing drought is a broadly accepted major contributor to the problem: with less rain and snowfall in the region, there is less abundant vegetation to anchor dirt, and less moisture in the dirt, to weigh it down and make it less likely to go airborne.
Beyond drought, there isn’t firm agreement as to cause. Is there overgrazing or increased grazing in the area that could be reducing vegetation and freeing the dirt? Are sustained wind speeds higher than in past years, and if yes, why?
Parks said that a Weather Service employee present at the meeting indicated the winds are indeed higher than in the past.
Dan Leblanc, a meteorologist with the National Weather Service in Flagstaff, didn’t have information about increased wind speeds available, but did say that through satellite imagery, the Weather Service has been able to pinpoint what they believe is the source of the dirt that has been causing the greatest impact on interstate traffic.
Leblanc said the genesis of the most problematic dust storms appears to be centered on the area of Tucker Flat Basin, which bisects Interstate 40 at milepost 245, west of Winslow.
Tucker Flat Basin actually begins several miles back from the interstate, and it is at that point that satellite images show the dust begins to stir and build up a wall as it is blown toward I-40. Parks related that during the interagency meeting it was said that the kind of soil present in Tucker Flat is prone to remain in the air longer when other soils might settle back to the ground sooner.
ADOT Community Relations Officer Rod Wigman explains that seeding along the roadway to try to keep dirt in place wouldn’t solve the problem since the dirt is coming from several miles off the interstate. At this time, seeding at the “starting point” in Tucker Flat Basin isn’t considered viable, either, because it would require a “massive” seeding project across an area with checkerboard land ownership that would be difficult to sort out.
“The only thing that’s going to relieve this situation is rain,” said Leblanc.
In fact, it’s been a few well-timed rain events this year that have kept I-40 open. There have been a few occasions this spring when ADOT and DPS were prepared to close the interstate because of anticipated windy, dusty conditions, but rainfall pressed the dirt back to the ground, improving visibility. Aside from two incidences of DPS personnel escorting traffic through recent dust storms, as of press time, no other actions have had to be taken and I-40 has remained open this spring.
Because there aren’t effective methods presently available to minimize the dust problem, ADOT and DPS have developed joint operation plans to seamlessly shut down the interstate when conditions are threatening. Knowing that the biggest area of concern is where Tucker Flat Basin crosses the interstate, the agencies divert traffic at mileposts 252 in Winslow and 230 at Two Guns, sending eastbound traffic back to Flagstaff.
“There’s a perfect little wind tunnel coming from the northeast with the wind blowing with special ferocity in the area of Two Guns and the Leupp turnoff,” said Parks. “If we keep drivers off that stretch of road during the worst of the windstorms, we think we can cut down on the accidents we’ve seen in recent years.”
Wigman concluded that there has been talk of asking researchers at Northern Arizona University to conduct a study to learn why conditions have been as they have in recent years. “But,” he said, “because things have tapered off a bit, and we’re not seeing as severe conditions this year as we did the past two years, there isn’t as great an emphasis on pursuing further study right now.”
The last date the interstate was closed due to winds and visibility was May 11, 2010.
With the joint operating agreement between ADOT and DPS, driver safety can be addressed when conditions warrant. It remains to be seen if the severe conditions forcing road closures will reemerge and require agencies to take a renewed look at additional long-term solutions.
