Northern Illinois hit with dirty rain; here’s why it’s happening

Does your car need a good scrubbing? Chances are it was a rare bout of dirty rain Wednesday that spurred your upcoming trip to the car wash.

You read that correctly: dirty rain.

“It’s just rainfall that has some contaminant particles – anything from dust to smoke – that gets mixed with the rain so that it’s no longer clear water,” said Scott Baker, a meteorologist with the National Weather Service in Romeoville. “And when it hits your car, window or siding, it looks dirty.”

Baker said dirty rain is something of a rarity in the Midwest – “You have to have a few different things come together” – and is more prevalent in Western states with a higher incidence of dust storms and wildfires.

There’s no problem explaining how it got to the Illinois Valley and across northern Illinois. Smoke from wildfires in the West was carried into the Midwest by jet streams strong enough to bring in particulate from the fires. Wednesday’s rainfall provided the missing ingredient.

Never heard of “dirty rain,” you say? Charlie Trovero had heard of it – but only because he studied meteorology in college.

Trovero is owner of Mr. Sparkle in Peru and, as fate would have it, he shut down the car wash Wednesday morning for scheduled maintenance. With rain in the forecast, Trovero figured there’d be few customers and his crew would have a window to oil the gears.

“Sure as can be, about 11 or 11:30, the cars started piling in,” Trovero laughed. “As soon as we lifted the pylons, the floodgates opened. I’ve got 40 in line right now.”

Dave Ortiz, chief deputy of the La Salle County Sheriff’s Office, isn’t as jubilant about the muddy-looking precipitation as Trovero. His office has 50 cars – with another six on order – now in need of a good scrubbing.

The deputies all will have to run the cruisers through a nearby car wash because inmates at the La Salle County Jail aren’t able to use sponges and squeegees to clean off the grime.

“That’s something we don’t have them do anymore,” Ortiz said.

Baker couldn’t recall the last time he spotted dirty rain, but in the next breath, he said the term itself is relatively new, even if the phenomenon isn’t. He likened it to the recent arrival of the term “derecho” to denote a straight-line wind event.

“I’m sure it’s happened in the past,” he said, “but ‘dirty rain’ is a newer term that people have gone with, and maybe we’ll start hearing of it more often.”