Massive walls of dust and debris called haboobs that roll through the U.S. Southwest can be awe-inspiring and terrifying, especially for motorists caught in their path.
Thunderstorms spawn the phenomenon and can create a wall of dust thousands of feet tall and several miles wide, reaching speeds of 60 mph or more.
How Do Haboobs Form?
Thunderstorms can produce strong downdrafts that hit the ground at 50–80 mph and then spread in all directions, said Sean Benedict, a meteorologist at the National Weather Service’s Phoenix office.The winds stir up loose dust and dirt, including from arid areas and farm fields, that get blown along in front of the approaching storm cell.
If thunderstorms don’t keep developing, the dust dissipates. But rain-cooled air in front of a storm can keep pushing warm air upward, generating new storms and more downdrafts, Benedict said.
When that happens, the haboob can keep growing, and some travel as far as 100 miles, Benedict said.
“It’s all dependent on whether they’re moving through an area that’s prone to [generating] dust,” said Benedict, noting that there’s a prominent dust corridor between Phoenix and Tucson.
How to Stay Safe
The National Weather Service issues dust warnings if it anticipates that thunderstorms and high winds moving through dust-prone areas could reduce visibility to a quarter mile or less. That’s especially important when conditions are favorable for clusters of storms, Benedict said.Haboobs can form quickly, catching drivers by surprise, blotting out the sun and reducing visibility to zero. Experts recommend that motorists pull off the roadways as far as possible, stop their vehicles and turn off their lights.
“People on the roads when they can’t see anything, they’re just gonna try to follow those taillights in front of them,” and run into parked cars, Benedict said. “If there is an accident, you might not know and you just get these big pile ups. So it’s definitely very dangerous when the visibility drops down that low.”
