Haboob

A giant wall of dust rolled through the Phoenix area Monday evening turning the sky brown; creating dangerous driving conditions; and delaying some flights.

According to the National Weather Service the dust wall was 3,000 feet high and created winds of 25 to 30 miles-per-hour with gust up to 40 miles per hour. Visibility was reduced to less than a quarter mile.

This phenomenon is known as a Haboob. The word Haboob comes from the
Arabic word هبوب "strong wind or “phenomenon". A Haboob is an intense sand storm observed in arid regions throughout the world and have been observed in the Sahara Desert; Arabian Peninsula; Kuwait; arid regions of Iraq; Africa; and the arid and semiarid regions of North America. In fact any dry land region could experience a Haboob. In the United States they are frequently observed in the deserts of Arizona, as well as New Mexico; and Texas.

During thunderstorm formation, winds move opposite to the storm’s motion and will travel in all directions into the thunderstorm. When the thunderstorm collapses and begins to release precipitation, wind directions reverse, gusting outward from the storm. The strongest gust generally occurs in the direction the storm is moving. When the downburst reaches the ground dry, loose sand is picked up and blown upwards creating a wall of sediment preceding the storm cloud. This wall of sand can be up to 60 miles wide and several kilometers in elevation. Usually rain is not observed at ground level because it evaporates in the hot, dry air (virga). There are occasions when rain persist and can contain a large quantity of dust (severe cases are called mud storms).

Have a good evening.