At this point, you may have very well seen the incredible and almost apocalyptic video from the Phoenix metropolitan area on Tuesday evening. Did you know you were actually witnessing a haboob? If you haven't heard the term before, you're probably not alone. The video showed a cloud of dust that was in excess of 50 miles wide and stretched nearly a mile into the sky. As scary as these sights may seem to us here in Virginia, haboobs are rather common in the desert southwest. Here's a quick description of how they are formed...
Strong winds coming out of thunderstorms rush down towards the ground. These strong gusts of wind spread outward as they hit the ground and pick up large amounts of dust. The desert southwest has been exceptionally dry as of late, so this allowed the winds to pick up even more dust and sand. The mound of dust and sand continues to grow as it sweeps across the land and it can travel great distances. Winds within this cloud of sand and dust can approach hurricane force, with gusts of 70-80 mph not out of the question. In addition to the extremely gusty winds, the visibility within a haboob can drop to near zero, virtually halting travel. The haboob on Tuesday struck a major city, at a busy time of day further complicating travel issues.
We'll never have to deal with these storms here in Virginia, but they'll continue to strike deserts around the world for decades and centuries to come!