A haboob (Arabic "strong wind") is a type of intense sandstorm commonly observed in arid regions throughout the world. They have been observed in the Sahara desert (typically Sudan), as well as across the Arabian Peninsula, throughout Kuwait, and in the most arid regions of Iraq. African haboobs result from the northward summer shift of the inter-tropical front into North Africa, bringing moisture from the Gulf of Guinea. Haboob winds in the Arabian Peninsula, Iraq, and Kuwait are frequently created by the collapse of a thunderstorm. The arid and semiarid regions of North America â€“ in fact, any dryland region â€“ may experience haboobs. In the USA, they are frequently observed in the deserts of Arizona, including Yuma and Phoenix, as well as New Mexico and Texas. During thunderstorm formation, winds move in a direction opposite to the storm's travel, and they will move from all directions into the thunderstorm. When the storm collapses and begins to release precipitation, wind directions reverse, gusting outward from the storm and generally gusting the strongest in the direction of the storm's travel.
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 often travel at 35â€“50 km/h (20â€“30 mph), and they may approach with little to no warning. Often rain is not seen at the ground level as it evaporates in the hot, dry air (a phenomenon known as virga), though on occasion when the rain does persist, the precipitation can contain a considerable quantity of dust (severe cases called "mud storms"). Eye and respiratory system protection are advisable for anyone who must be outside during a haboobâ€”moving to a place of shelter is highly desirable during a strong event.