[h=3]Dust Storms Caused by Mesoscale Systems » Convection and Haboobs
[h=3]Dust Storms Caused by Mesoscale Systems » Convection and Haboobs » Description This dust squall is a Haboob, that is, a dust storm caused by convective downbursts. Haboobs are the true walls of dust and sand that most people think of as strong dust storms. The term is used in Argentina as well as Africa, Asia, and the desert southwest of the Unites States.
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[h=3]Dust Storms Caused by Mesoscale Systems » Convection and Haboobs » Properties of a Haboob Winds associated with the gust front of a dry downburst from a convective storm average 35 to 50 knots and can easily excite a dust storm when they encounter an appropriate source area. Haboobs tend to be rather small, on the order of 100 to 150 kilometers, except in the Sahel area where they can extend up to 1000 kilometers horizontally. Click Play to view the animation.
Haboobs tend to be 1500 to 2500 meters high at the peak of the event. However, they can reach 4500 meters when exacerbated by convergent outflow boundaries. The average Haboob tends to be short-lived, lasting about three hours. Visibility usually begins to improve soon after the gust front passes.
In the Sahel, though, Haboobs created by squall lines tend to be much larger (up to 1000 km) and longer-lived (lasting up to 24 hours). They can keep visibility poor for many hours after the gust front passes.
Although Haboobs can be seen approaching an area from afar, they move in very quickly, typically at about half the velocity of the winds within the storm. So a Haboob packing 50-knot winds will move at about 25 knots.
