Metropolitan Phoenix is shaking itself off Friday after a giant wall of dust smacked the city for the third time within the last six weeks, turning the skies brown and coating anything left outside in a thin layer of fine dirt.
The wall of dust, known as a haboob, was 1,000 feet high and traveled at least 50 miles into metro Phoenix and neighboring Pinal County on Thursday evening before dissipating.
National Weather Service meteorologist Ken Waters said the area is experiencing a typical number of dust storms this year, but what sets this season apart from others is the size and power of three of the storms.
"Each year, you are going to get some variety of the dust storms," Waters said. "We don't see a single causative factor for why they seem to be stronger this year."
Weather experts said such massive dust storms only happen in Arizona, Africa's Sahara desert and parts of the Middle East because of dry conditions and large amounts of sand.
Waters said thunderstorms moving through southern Arizona supplied winds of up to 60 mph that stirred up fine dust in the agricultural fields and sent Thursday's haboob to the state's largest city.
The storm severely reduced visibility, creating dangerous driving conditions and causing some airline flights to be delayed.
Meteorologists also were trying to determine whether storm damage in neighboring Pinal County and across various spots in metro Phoenix during the dust storm was caused by microbursts.
Power lines landed on top of several cars and one elementary school bus in Pinal County, located just south of metro Phoenix. County spokesman Elias Johnson said there were no reported injuries and everyone got out safely including the four students on the bus.
Some incoming and departing flights at Phoenix Sky Harbor International Airport were delayed about 40 minutes because of the storm. Take-offs and landings resumed after the storm subsided.
One utility, the Salt River Project, said at the peak of the storm 3,500 of its customers were without electricity, mostly in the Queen Creek area southeast of Phoenix, but power had been restored to nearly everyone within about five hours of the storm's arrival.
Authorities in Pinal County were assessing the damage in the city of Eloy, where homes were damaged, roofs were torn off businesses and a junior high school has part of its roof missing.
KTVK-TV reports that elsewhere in Eloy, trees landed on top of homes and winds sheared off the roof of a business in the downtown area.
This season's most powerful dust storm came on July 5 and brought a mile-high wall of dust that halted airline flights, knocked out power for 10,000 people and covered everything in its path with a thick sheet of dust.
Another dust storm hit July 18 reaching heights of 3,000 to 4,000 feet, delaying flights and cutting off power for more than 2,000 people in the Phoenix metro area.
Pollution levels skyrocket during dust storms and exacerbate breathing problems for people with asthma and other similar conditions.