Phoenix has experienced two unusually intense dust storms, classified as Category 5 events, within a span of three days. These events, known as haboobs, are characterized by massive walls of dust and debris stirred up by strong downdrafts from thunderstorms.
The most recent storm occurred early Thursday, following a similar event on Monday. While both storms significantly reduced visibility to about half a mile, they struck during hours with less traffic, minimizing reported impacts. National Weather Service meteorologist Matt Salerno noted that the timing likely prevented more significant issues.
Researchers at Arizona State University, who developed a dust storm severity scale using data since 2010, described the occurrences as unprecedented. Randall Cerveny, a professor at ASU and a key figure in developing the scale, stated that having two Class 5 dust storms so close together is outside their recorded history. These were only the fifth and sixth Category 5 dust storms observed in the region in the last 16 years.
Scientists suggest that the region's drier-than-normal conditions contribute to the increased amount of loose dust available to be lifted by winds. Furthermore, experts have linked human-caused climate change to a higher probability of both severe droughts and more intense storms, which can create conditions conducive to severe haboobs.