Graphic: More information on the huge dust storm

An enormous wall of dust that barreled across the Valley during a monsoon storm left so much dirt behind on the ground and in the air that it didn't just coat cars and clog up pools, it prevented pilots approaching Sky Harbor International Airport from seeing the runways a day later.

The windstorm that took Valley residents by surprise Tuesday around sunset was a rare monster that reached theatrical proportions. It spawned a 100- to 150-mile-wide plume of dust more than 5,000 feet high, moving at 50 mph to 60 mph from northwest Tucson along Interstate 10 through the Valley before petering out in Yavapai County, according to Elizabeth Padian, a National Weather Service spokeswoman.

"The magnitude of it, how high it was, how wide it was, how dense it was, this is remarkable," she said.

The storm was all anyone could talk about Wednesday after it cut power to 10,000 Valley customers, grounded flights and left people cleaning up cars and pools caked with dirt and mud.

Ken Waters, a warning-coordination meteorologist with the Weather Service, said the storm hung together like a weather front of its own. "This is like special effects from a Hollywood movie," he said. "It's kind of once in a lifetime."

The aftereffects forced the Federal Aviation Administration to reduce aircraft arrivals at Sky Harbor on Wednesday from about 78 per hour to 48 an hour because of poor visibility caused by a layer of dust still hanging around at 4,000 to 6,000 feet.

Pilots compensated by using instrument-arrival equipment, similar to that used to land during a thunderstorm, said Lynn Lunsford, an FAA spokesman in Fort Worth, Texas. Although conditions were improving late Wednesday afternoon, planes were still "descending through the dust," he said.

Randy Cerveny, an Arizona State University professor of geographical sciences who has studied Arizona's weather for decades, said the Valley used to have more frequent dust storms like Tuesday's before development paved over the desert. But this one was impressive, he said.

"It's the biggest I've seen in 10 or 15 years," he said.

Cerveny and the Weather Service said the winds were created by a powerful downdraft as thunderstorms near Marana and Oro Valley fell apart. Rain forced the winds to ground level, and they quickly swept up dust because of the extremely dry conditions. The amount of dust grew larger as the storm blew northwest toward the Valley.

"It's kind of like a bomb blast," Cerveny said, adding that most of the winds headed northwest toward Phoenix while a spur went west through Tacna, eventually passing through Yuma and crossing the Colorado River.

Cervany theorized that unkempt yards in houses abandoned during the economic downtown created more dust that fed the storm.

Mark Shaffer, a spokesman for the Arizona Department of Environmental Quality, said the testing station on 15th Avenue, between Thomas and Indian School roads in Phoenix, recorded an astronomical reading of 6,349 micrograms per cubic meter at 10 p.m. Tuesday. The federal EPA standard is 150.

Because of the dust that lingered through Wednesday, those with respiratory issues were warned to stay inside.

"It's a little bit frantic today," Dr. Laura Ispas-Ponas said. "Patients are calling complaining of symptoms that seem to be, but aren't necessarily, allergy-related."

The specialist at Sonoran Allergy and Asthma Center in Scottsdale said dust particles act as irritants, mimicking allergy symptoms such as nasal drainage, dry cough and itchy, watery eyes.

Dust also can cause serious reactions in people with asthma, chronic obstructive pulmonary disease and other respiratory conditions, Ispas-Ponas said.

Residents caught in the dust storm could end up with valley fever, a usually harmless lung infection that occasionally spreads to the spinal fluid, bones and other parts of the body, with potentially devastating effects, said Dr. Rick Helmers, a pulmonologist at Mayo Clinic in Scottsdale. Valley fever is caused by inhaling spores of the fungus coccidioides, which grows in the soil in the Southwest. The spores become airborne when stirred by wind, construction or farming and can cause fatigue, fever, coughs and muscle and joint aches.

Across the Valley, many people were busy cleaning up cars, pools and yards Wednesday.

Scottsdale's Eldorado Aquatic and Fitness Center was expected to reopen today after workers spent most of the day cleaning up a "huge mud hole" in the swimming pool, employee Joyce Shorr said.

Car-washing and pool-cleaning services were inundated.

Quick N Clean car wash saw about a 50 percent increase in customers, with anywhere from six to 15 cars lined up at several Valley locations before opening time, company President Richard Karle said.

"Our car-wash business was good today," he said. "It will be a nice little run for the next week or so. There are a lot of dirty cars out there."

For pool-cleaning businesses, the storm brought a mix of good and bad.

"The new-service requests are coming in hot and heavy," said Chip Bury, owner of Splish Splash Pool Service in Phoenix. But on the down side, companies face a lot more work cleaning up existing customers' pools.

"You have to take the good with the bad," Bury said. "We don't pray for storms. It's such a tremendous burden."

For auto dealers with cars out on open lots, the "haboob" was a big inconvenience. Dealerships opened with cars covered in dirt and debris.

Mark Gruwell, co-owner of Courtesy Chevrolet knew he was in for a long day as he watched the storm move in Tuesday night.

"I was like, 'Oh, my gosh, this is just going to make a big mess for the next day.' I knew it was going to be a lot of work," Gruwell said.

The company hired two extra workers to help clean up for the next two days. "I've lived here my whole life, and I have never seen anything like that," he said. "It was just unbelievable."

Republic reporter Connie Midey contributed to this article.