Storms in the Western U.S. have created an odd coincidence and something of a weather swap in Arizona and Washington.

Heavy rain overwhelmed a canal late Tuesday in famously dry Phoenix, leaving more than a dozen people marooned on flooded streets. Meanwhile, a huge dust storm moved through Washington state, leading to low visibility and numerous traffic accidents.

Weather experts say the dust storms, called haboobs, typically occur in Arizona, Africa's Sahara desert and parts of the Middle East because of dry conditions and large amounts of sand, but they can occasionally show up elsewhere.

"They have to get dry for a prolonged period to be able to get that dust," National Weather Service meteorologist Mark O'Malley, who is based in Phoenix, said Wednesday. "Here, it's always that dry."

This time of year can cause exceptions, however, as thunderstorms are relatively typical during the Arizona monsoon season, which runs through Sept. 30.

There were no reports of extensive damage, but the Phoenix Fire Department said 16 people were rescued Tuesday evening from vehicles stuck in flooded streets. Canal waters spilled onto roads, bringing a swift current that appeared between 3- and 4-feet deep. One man experienced a medical emergency and was taken to a hospital in critical condition. Some people were helped through their car windows by firefighters. Several were brought to a Phoenix fire station for shelter.

"It looked like the Colorado River out in front of the station," said Phoenix fire spokesman Benjamin Santillan.

The storm also caused flight delays, knocked down trees and power lines and left about 4,500 households in the suburb of Tempe temporarily without power.

Monsoon season in Arizona also produces massive haboobs that sweep through a few times each summer, but Tuesday evening a thunderstorm brought the phenomenon to eastern Washington.

The state gets dust storms such as this every couple of years, said Matt Fugazzi, a National Weather Service meteorologist in Spokane.

The dust blanketed parts of Whitman and Adams counties, south of Spokane, near the Idaho state line. "It had a lot of similarities to a lot of times what you guys (in Phoenix) see down there — the approaching wall of dust," said Spokane meteorologist Ryan Fliehman.

Fliehman said such a storm might seem anomalous since people often associate Washington with Seattle rain. But he said the central and eastern parts of the state are much drier, and the conditions can create a desolate landscape ripe for a dust-up.

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Associated Press writer Paul Davenport and photographer Ross D. Franklin contributed to this report.