PHOENIX (AP) — A giant wall of dust rolled through the Phoenix area on Monday, turning the sky brown, creating dangerous driving conditions and delaying some airline flights.

The dust, also known as a haboob in Arabic and around Arizona, formed in Pinal County and headed northeast, reaching Phoenix at about 5:30 p.m.

The dust wall was about 3,000 feet high and created winds of 25 to 30 mph, with gusts of up to 40 mph, said Austin Jamison, a meteorologist with the National Weather Service. Visibility was down to less than a quarter-mile in some areas, he said.

"You have suddenly very poor visibilities that come on with all the dense dust in the air," he said. "With poor visibilities, that makes for dangerous driving conditions and that's arguably the biggest impact."

There were no immediate reports of accidents on roadways because of the storm, which began to clear within an hour of moving in. The Arizona Department of Public Safety did not immediately return a request for information about road conditions.

Some departing flights at Phoenix Sky Harbor International Airport were delayed because of the storm, said airport spokeswoman Julie Rodriguez.

Incoming flights from nearby cities including Los Angeles were being held until the storm cleared, she said. She did not know how many flights were delayed or whether any were canceled.

Another giant dust storm in Arizona caught worldwide attention on July 5. That storm brought a mile-high wall of dust that halted airline flights, knocked out power for hundreds of people and turned swimming pools into mud pits.

Jamison said Monday's storm was not as powerful or as large as the last one, and didn't last as long.

"It's kind of like a ripple in a pond where it spreads out, slows down and fades out," he said.

Rodriguez said visibility at the airport was better Monday than it was during the July 5 storm, which grounded flights for 45 minutes.

"It's not as bad as it was," she said. "It's reduced but it's not terrible."

Weather officials say haboobs only happen in Arizona, the Sahara desert and parts of the Middle East because of dry conditions and large amounts of sand.

Pollution levels skyrocket during dust storms and create even more breathing problems for people with asthma and other similar conditions.

The dust also brings increases in a disease known as Valley Fever, a fungal pneumonia. Valley Fever thrives in the hot and arid Southwest in dirt found just a few feet beneath the earth's surface; it can be stirred up by construction, wind and other activity.

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Associated Press writer Michelle Price contributed to this report.

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