PHOENIX, AZ (WMC) - A wall of dust covered the Phoenix, Arizona, metro area as the second monsoon storm in a span of four days hit the city.
A monsoon is a large-scale weather pattern that involves a seasonal shift in winds over a particular region and is usually accompanied in an increase in atmospheric moisture and precipitation.
Monsoons can occur in multiple places across the earth, typically in areas of a large, elevated landmass near an abundant source of warm, tropical waters. All of these factors enhance rainfall and thunderstorms in monsoon regions.
In the United States, the jet stream is pushed further north at a time when most of the country is experiencing warm temperatures. A large area of high pressure and clockwise winds around that system help push atmospheric moisture up across the Southwest.
The strong storms started hitting the Phoenix area on Monday night with more than 120,000 customers losing power. The winds downed power lines, uprooted trees across the metro and blew off part of a roof of a building at an apartment complex in Glendale.
Arizona's monsoon season runs from mid-June to the end of September.