Clean-up after 'mother of all dust storms'

Arizonans are calling it the mother of all dust storms.

The mile-high wall of ominous, billowing dust that appeared to swallow Phoenix and its suburbs is all that locals can talk about.

It moved through the state around sundown Tuesday (local time), halting airline flights, knocking out power to nearly 10,000 people, turning swimming pools into mud pits and caking cars with dirt.

The sky was still filled with a hazy shade of brown on Wednesday as residents washed their cars and swept sidewalks.

Because dust storms, also known by the Arabic term "haboobs," are so hard to predict, Tuesday's took everyone by surprise.

Seemingly out of nowhere, the 160km-wide storm moved like a giant wave, the dust roiling as it approached at up to 100kmh. Once it hit, visibility dropped to zero in some areas, the sky turned nearly black, trees blew sideways, and even downtown Phoenix skyscrapers became invisible.

"Just the height of it looked like a special-effect scene from a movie, like a dust storm out in Africa," said Charlotte Dewey, a National Weather Service meteorologist in Phoenix. "It looked so huge, looking at the city down below, it was just specks of light and miniature buildings.

"I have a feeling that people will be talking about this for another week or two, at least," Dewey said.

She said meteorologists were still trying to get exact measures from satellite and radar to figure out how big the dust storm was and compare it with previous ones, but they estimate it was more than 1.6km high and more than 160km  wide.

"People who've lived here their whole lives, 30 or 40 years, are saying they've never seen a storm this large," Dewey said.

She said winds from separate thunderstorms in the eastern and southern parts of the state collided somewhere between Phoenix and Tucson and combined with a severe lack of moisture to create the wall of dust. The storm also hit the Yuma area in southwestern Arizona, and far western Arizona.

Haboobs only happen in Arizona, the Sahara desert and parts of the Middle East because of dry conditions and large amounts of sand, Dewey said.

"It's a pretty rare thing to be able to see," she said.

While some Arizonans revel in the strange weather, many were unlucky enough to be outside when the storm rolled in. The storm blasted them with dust that went up their noses, behind their contact lenses and in their mouths, leaving behind a gritty taste.

Holly Ward, a spokeswoman at the Maricopa County Air Quality Department, said pollution levels skyrocketed.

During the storm, the amount of particulate matter in the air reached 375 micrograms per cubic meter, more than double the level federal standards consider healthy.

"You didn't have to go far anywhere in the dust storm to feel the remnants of that dust in your throat and in your nose," Ward said. "If someone already has breathing problems like asthma and bronchitis, this is an incredible health challenge and serious health threat for those folks."

The dust storm also grounded flights at Phoenix's Sky Harbor International Airport for 45 minutes. At least three flights were cancelled and more than a dozen were delayed, while several incoming flights were diverted to Tucson and Ontario, Calif., said airport spokesman Julie Rodriguez.

Federal Aviation Administration spokesman Lynn Lunsford said planes need to be grounded during dust storms because of the low visibility, high winds and potential damage from the dirt.

"If you think about it, glass is made from sand that has been melted, and if you think about the temperature inside a jet engine, it's hot enough to melt sand," he said. "If you can't see through it, you definitely don't want to fly through it."

He likened the storm to volcanic ash that wreaked havoc in the skies in April 2010, when an eruption grounded flights across Europe for days, disrupting travel for 10 million people.

Arizona's dust storm annoyed others who couldn't see out of their car windows or found their pools filthy in the morning. But that created pay dirt at local businesses.

"It's crazy here," said Margaret Viloria, manager of Los Olivos Hand Car Wash near downtown Phoenix. "When we opened this morning cars were lined up outside. It's just been nonstop."

On a typical day, the car wash cleans about 25 to 30 cars an hour. It was averaging 55 an hour on Wednesday, Viloria said.

Joe Pinelli, owner of The Pool Service in Phoenix, was also having an "absolutely chaotic" day.

"I don't think I've been off the phone since about 6am," he said.

Dewey, the weather service meteorologist, said there was a slight chance of blowing dust in the Phoenix area on Wednesday and Thursday and a slight chance of thunderstorms the rest of the week.

"As far as if it would be of any magnitude we saw Tuesday, I don't know," she said.