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 (97 kpm) or more.

Here's what to know:

How do haboobs form?

Thunderstorms can produce strong downdrafts that hit the ground at 50-80 mph (80-129 kph) 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-c

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