When I was a kid, here in Scottsdale Arizona, we had what we called Dust Storms almost every evening during the Monsoon (July and August mostly). It would be so hot during the day that the storms would build up over the desert then plow in when the temps dropped a bit. I remember sitting in our front room, looking out the window, and the dust was so thick I couldn't see the house across the street. Since then, though, the valley has sprawled and replaced desert with concrete, so our summer storms are generally more mild. Until last night, that is. It was a good old fashioned dust storm, although they're calling it a Haboob.
"A haboob (Arabic هبوب) is a type of intense sandstorm commonly observed in arid regions throughout the world. When this downdraft, or "downburst", reaches the ground, dry, loose sand from the desert settings is essentially blown up, creating a wall of sediment preceding the storm cloud. This wall of sand can be up to 100 km (60 miles) wide and several kilometers in elevation. At their strongest, haboob winds can travel at 35-50 km/h (20-30 mph), and they may approach with little to no warning."
It looks much scarier than it was, however, once the dirt blew in, it stopped and hung around for hours and hours laying a brown yucky blanket over everything!
This is a great link to an awesome video that captures the "Haboob" rolling in.