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A relative of the desert haboob: The less predictable dust-channel

By MIKAYLA MACE

Arizona Sonora News

(Photo: National Oceanic and Atmospheric Administration)

[UPDATED]

Everyone in Arizona knows what haboobs are: A towering wall of dust, sometimes a half-mile high and a hundred miles wide, caused by summer monsoons rolling in over Tucson and southeast Arizona, and slamming the dry, loose dirt into the air. This monster sweeps across the desert northward toward Phoenix.

These large dust storms can be predicted, seen and avoided.

The haboob’s lesser known cousin, the sudden dust-channel, is much smaller but more unpredictable and dangerous.

The most dangerous dust-channels pop up quickly next to freeways and are borne out of the dry, loose dirt from devegetated land or fallow fields. On windy days, this dirt is easily blown in thick curtains across freeways, cutting visibility down to as low as five feet.

In 2015, 47 crashes were caused blowing dust statewide. Seventeen were injured, the rest was only damage, according to the Arizona Department of Transportation. The statistics only apply to roads managed by ADOT, interstates and state and federal routes.

“Channelized dust is only part of the challenge,” said ADOT spokesman Tom Herrmann. “Storms moving through the area, both monsoon storms and winter storms, also can result in blowing dust and reduced driver visibility.”

The last fatal accident attributed to blown dust was in 2013. Three people died.

The dist scenarios are most common during dry winters, which is what Arizona is headed for this year.

Scientists and politicians are now trying to find ways to warn the public of potentially dangerous dust. ADOT has a solution that involves the installation of sensors along a stretch of Interstate 10 where the blowing dust problem is greatest, between milepost 209 near Eloy and milepost 219 near Picacho Peak. Design work began in October, and construction is expected to start next fall and be completed a year later.

That $12.8 million project will have a dust-detection system that will alert ADOT and DHS when blowing dust in the area west of I-10 poses a safety threat. It will feature highway message boards and visibility alerts, as well as a capacity for alerting the transportation department’s traffic operations center in Phoenix to take steps that could include closing of the freeway during a dust storm.

Some atmospheric scientists and modelers said sensors are a good idea, but they also have different solutions that they contend might be more effective and much cheaper. The state, however, says its project is effective — and quicker.

William Sprigg, research professor emeritus in atmospheric sciences, and Michael Leuthold, manager of the Regional Weather Modeling Program, claim that because dust channels occur too quickly and last too briefly for, this warning system might not be fully effective.

“I’m really happy they’re doing that, but it’s only part of the problem,” Sprigg said.

Haboob hitting Phoenix on July 5, 2011. (Photo: Arizona Dept. of Health Services}

Prevent with plants

Leuthold said he’s seen this scenario play out before.

“In here are tons of orchards,” he said pointing to Google Earth satellite images zoomed in on San Simon. “You can see all these old farms that used to be in here. And 10-15 years ago, they had terrible problems with dust storms.”

Fallow farms and bladed land contributed to frequent dust channels along that stretch of Interstate 10.

The state installed sensors in San Simon that he said were like the new ones that will be installed along I-10 by Picacho Peak. However, ADOT says those were sensors “to determine if conditions were right for a dust storm. Blowing dust could only be determined by ADOT or DPS teams on location. The system in the San Simon case had none of the components being discussed [for the newly planned system],” ADOT said.

Meanwhile, Leuthold says that after the area was left alone for a few years, it revegetated naturally, and the problem vanished. The only caveat to this, he said, is that last year, the area was bladed again in preparation for another orchard.

“The solution to this particular problem is to not allow this area adjacent to the freeway to be disturbed,” he said pointing to a swath of land south of Interstate 10. “Or if it is, immediately plant and prevent.”     

The question he and other pose is, why install costly sensors when you can just leave it alone and plants will install themselves free of charge?

Perfecting Predictions

To Sprigg however, there’s more to the ultimate solution, and it involves private land use. “I don’t believe that you can take care of the dust right adjacent to the highway and say we’ve done our jobs,” he said.

He plans on using improved, high-resolution atmospheric models which will simulate future dust events.

By using National Weather Service weather models and then adding in his own dust component to that model, he can see how blown dust might travel around Arizona.

“We want to run the model for years. We want to do it for 5 years or 3 years at least in an operational sense so that we can tell somebody what our accuracy is,” Sprigg said. 

In another email, Steve Elliott, an ADOT spokesman, said the state is able to get quicker results. “We have the ability to establish a pilot detection and warning system sooner than this in an area that has seen many crashes due to sudden blowing dust,” he wrote. “We are investing in a way to warn drivers about sudden blowing dust in an area where [it] is a problem.”

Sprigg said he wants confidence in the models. When this is achieved, it means that there is more accuracy in the predictions.

 

“I’m particularly frustrated because I believe that we can save lives,” Sprigg said.

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Mikayla Mace has a bachelor’s in neuroscience, a minor in astronomy and is working on her master’s in journalism, so she can be a science writer and illustrator some day. Mikayla is from Tucson, Arizona and likes to read, paint, learn different instruments and play soccer in her free time.