A dust storm descended on the Phoenix, Ariz., area during the evening of July 5, The Weather Channel reported.
Live video feeds and pictures posted to social networking sites showed views of the wall of dust as it descends on the city.
Dust storm usually arrive suddenly in the form of an advancing wall of dust and debris, which can cover a large area and reach thousands of feet into the air, according to the National Oceanic and Atmospheric Administration (NOAA). They happen when strong gusts of wind pick up loose sand or dust from a dry surface.
These dust storms are not uncommon in the Southwest during what is called the summer monsoon season, where the overriding winds change direction, Julie Rodriguez, a spokesperson for Phoenix Sky Harbor Airport told The Weather Channel. Flights were grounded while the dust storm obscured visibility.