Imagine you're driving down the road and then, suddenly, the air around your car is totally filled with dust. This is what can happen during the weather phenomenon known as a haboob.A haboob is a type of dust storm that forms after a thunderstorm . They are usually quite large and can be thousands of feet high and up to 100 miles wide.During thunderstorms, cold air rushes down to the ground and spreads out. When this happens in an arid or semiarid region, the wind can kick up dust, forming a haboob.Haboobs form very quickly. Within a matter of seconds, they can dramatically reduce visibility. This means they pose a threat to motorists.It's important to be alert during a haboob because the strong winds can knock down trees and power lines.Haboobs are usually over within a couple of hours.In the U.S., haboobs are most likely to occur in the Southwest during July and August, according to AccuWeather.