Dust Storm — Greater Phoenix Area, Arizona

2011-07-05 · Greater Phoenix Area, Arizona

Event narrative

Strong thunderstorms developed to the southeast of the greater Phoenix area during the afternoon hours on July 5. As the storms dissipated and moved towards the northwest, rain-cooled outflows picked up copious amounts of dust and dirt and generated a massive haboob which raced northwestward and across the greater Phoenix area during the evening hours. The haboob was considered to be of historic proportions; it measured at least 100 miles in length, was over one mile high and moved across the deserts at more than 50 mph. Peak wind speeds within the haboob reached 70 mph or more. Numerous trained weather spotters from across the greater Phoenix area reported visibilities down to near zero miles, in many cases visibilities were less than 50 yards. During the storm, the Buckeye fire department responded to a weather related multi-vehicle accident at Interstate 10 and Watson road in Buckeye. Thirteen people suffered minor injuries and were treated at the scene. Due to the massive amount of topsoil that was stirred up by the haboob, area Physicians and medical personnel warned that there could be a sharp rise in new Valley Fever cases among those exposed to the dust. Valley Fever is a fungal infection caused by inhalation of spores that reside in the stirred up topsoil.

Wider weather episode

Strong to severe thunderstorm development had occured in the early afternoon hours of July 5th near the Tucson, AZ area and east of Tucson. As thunderstorms dissipated and began moving northwest, outflows from these storms began producing very strong downburst winds, some in excess of 70 mph. Around 6:30pm MST, the NWS Phoenix office began receiving calls of dust moving into the Casa Grande, AZ area, about 50 miles southeast of downtown Phoenix. Upon examining radar data, it is estimated the dust storm reached a maximum height of 5000 feet to 6000 feet, the aerial coverage was close to 100 miles and the distance traveled was around 150 miles.

Source: NOAA Storm Events Database, event_id 322390. Narrative written by the NWS forecast office that issued the report.