The science behind the storms

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PHOENIX - Two massive dust storms have rolled through the Phoenix metro area in as many weeks.

The National Weather Service says unusually dry conditions are fueling the dust spectacles.

"It's just bone-dry on the ground," says scientist Doug Green of the National Weather Service.

So far there have been just 1.62 inches of rainfall at Sky Harbor Airport this year, compared with 3.69 inches by July 18 in an average year.

Green says thunderstorms on extra dry terrain south of the Valley kick up more dust that's blown north towards Phoenix.

"If we could just get a good soaker where everyone got a half inch, three quarters of an inch or an inch of rain between here and Tucson that would probably diminish the amount of dust that storms would form," he said.

Green says the July 5 dust storm was likely one of the biggest in the state's history, but not the only remarkable one to roll through the Valley.

He recalls other big dust storms in the past but suggests those may not be as memorable because in years past we haven't had widespread access to smart phones and social media websites that enable people to share weather images.