The National Weather Service is warning area residents that a weather phenomenon known as “cold air funnel clouds” could occur on Monday night.
According to the weather service, the funnel clouds are possible throughout the Chicago area, especially in areas south of Interstate 80.
While the clouds rarely touch down and generally pose little threat, residents are still encouraged to call law enforcement if they spot one:
Several area police departments, including the Aurora Police Department, have also warned residents about the clouds, and say they are continuing to monitor weather conditions.
So-called “cold air funnel clouds” typically form beneath showers or weak thunderstorms when air in the atmosphere is especially cold, according to the National Weather Service. They most commonly occur in the spring and fall when the sun is able to heat up the lower levels of the atmosphere, and while they are generally harmless, they can occasionally touch down and generate EF-0 level wind speeds of up to 85 mph.
Several of the clouds have already been spotted, including in LaSalle County.