Thursday July 31, 2014




Dramatic dust storms common in arid climates, desert terrain, agricultural regions

PHOENIX - Powerful dust storms that carry whirling dirt and debris are common occurrences across parts of Arizona and the arid Southwest during the spring and summer months. A day after a massive dust storm swept across an Arizona highway, killing three people in a 19-vehicle pileup, experts say the state isn't alone, across the country or the world, in its susceptibility to such a weather phenomenon.

Africa's Sahara desert and parts of the Middle East are often hit with powerful dust storms, also called haboobs derived from the Arabic word haab, which means wind, because of dry conditions and large amounts of sand.

In the U.S., experts say dust storms also occur in arid parts of the country, often in agricultural regions that have been manipulated through soil tilling and crop planting that leave the ground disturbed and more easily picked up by winds.

Over the decades, dust storms have occurred in Arizona, California's Central Valley, New Mexico, and in agricultural areas of Oregon, Idaho, Texas, Utah, Washington state, Kansas and elsewhere.

"I certainly believe that a lot of this can be tracked to human activity," says National Weather Service Meteorologist Ken Waters, who has spent years studying dust storms. "We typically don't see that sort of dust in parts of the desert where it's just mountains and the area hasn't been disturbed."

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DUST STORM CAUSES

Small, fast-moving dust storms, like the one Tuesday in Arizona, can be caused simply by high winds sweeping across dry desert terrain. These types typically dissipate quickly but can often be the most dangerous to drivers who have little warning and find themselves stuck amid zero visibility on crowded highways. Larger dust storms can be formed when air is forced down from the atmosphere and pushed outward by an approaching thunderstorm, dragging debris with winds speeds up to 60 mph. Such storms can create a wall of blowing dust that reaches up to 10,000 feet and blackens out the day sky.

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EFFORTS TO LIMIT STORM SEVERITY AND MITIGATE DANGERS

Scientists with the National Weather Service, along with state and private partners, have been working for several years on developing advance warning systems and ways that landowners along busy roadways might help mitigate the severity of such storms. In 2011, the Arizona Department of Transportation began testing a new dust warning system that takes field readings on weather conditions, humidity and wind speed. The goal is to detect potential dust storms to provide drivers advance warning. ADOT spokesman Dustin Krugel says the agency wants to predict and educate. "There's really no way we can reduce the dust impact. That's kind of beyond our control," he says. "And there's no feasible engineering solutions that we could install to prevent dust from crossing" highways. There has also been discussion of having farmers along major thoroughfares water down dry fields to limit blowing dust.

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SAFETY TIPS FOR DRIVING IN DUST STORMS

Authorities recommend that motorists pull off the highway immediately upon seeing an approaching dust storm. If drivers find themselves in the middle of one, officials recommend they pull completely off the paved portion of the road, turn off all lights including emergency flashers, set the emergency brake, keep feet off the brakes so others don't try to follow the tail lights, and stay in the vehicle with seat belts fastened until the storm has passed.

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Sources: National Oceanic and Atmospheric Administration, National Weather Service, Arizona Department of Transportation.



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