Rare mud rain due to dust in the Valley

PHOENIX - Rain and dust storms in the Valley may seem like common events for us. However, when the two combine, it creates a very rare weather phenomenon called mud rain.

On July 5, Josh White, an Arizona State University climatologist and weather enthusiast, was out driving around in Tempe when our historic dust storm rolled in and dropped visibility down to almost nothing.

That's when he witnessed the rare event: mud rain. "The dust started to clear out and we started to get a little bit of rain and I noticed on my windshield that the rain was brown," he said.

White said that only one pocket of the Valley received this mud rain. "Right along here," he said as he pointed to the Tempe area. "It was a very isolated event. It didn't happen all over the city. In fact, as far as I could tell, it was concentrated right here."

He then got straight to work analyzing how this event happened using raw data, various models, and upper level charts.

"Basically some of the dust got uplifted so high that it got entrained in the cloud and then precipitated out," he said.

White said places like the Sahara are more common spots for mud rain. It's rich in iron and sometimes falls out red, nicknamed "blood rain".

"It's rust, so that's what gives it that reddish tint," he said.

White said our mud rain doesn't contain any unique minerals, but it can create a thick coating of mud on surfaces. Therefore, it might take an extra car wash to remove it!

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