Chicago dust storm: A deep dive into the rare and historic weather event for the city

Chicago dust storm: A deep dive into the rare and historic weather event for the city

Last Friday’s dust storm was Chicago’s worst in nearly 100 years. Here’s how it happened.

CHICAGO - One week ago, the very first dust storm warning was issued for the city of Chicago.

What we know:

Dust storms aren’t unheard of in the Midwest region, but it is very rare for one to impact Chicago.

In fact, the Chicago National Weather Service confirmed this was the first dust storm warning that has ever been issued for the city and only the second time a warning of this kind has been issued by their office. The only other time was on May 7, 2023.

Dig deeper:

So how did this giant plume of dust form? It all started with a cluster of severe storms in central Illinois, near Bloomington. These storms packed a punch with winds over 60 mph, picking up dust and topsoil as they swept across dry farmland. The dust was lifted into the atmosphere and an expansive dust plume quickly formed along and behind the leading edge of the thunderstorm outflow winds.

But if it’s just that simple—high winds over farm fields—why doesn’t this happen more often? There are a few factors to consider, like dust availability, atmospheric conditions, terrain, and the dust size and particle characteristics.

At the time of our May 16 dust storm, the drought monitor showed central and northern Illinois were abnormally dry. So there was plenty of dry soil to work with as the storms rolled through recently tilled farmland.

As for atmospheric conditions, when you have warm air and ongoing thunderstorm activity, the dust can remain suspended in the air for longer periods of time because of the inflow and outflow winds. And finally, the terrain in central and northern Illinois is fairly flat with a lot of open farmland. This left little to stand in the way of the giant dust plume.

Last Friday, visibilities dropped to near-zero with winds gusting over 60 mph. The warning urged motorists to pull over if caught in the dust storm, and those with respiratory and other health issues were urged to stay indoors.

Timeline:

According to the National Weather Service, the last time a dust storm affected Chicago was on May 31, 1985. Newspaper accounts noted the visibility in downtown Chicago got down to four miles.

Our May 16 dust storm was the worst to impact Chicago in nearly a century. The last time one of this magnitude impacted the city was during the Dust Bowl in the early to mid 1930s. The National Weather Service says records from that time period are difficult to verify, though a dust storm on May 10, 1934, appears to be the closest analog to this event.