A swarm of small t-storms sprang to life at a furious pace Tuesday afternoon, pelting areas just west of Chicago with pea size hail and spinning up cold air funnels. The rate of thundershower growth was stunning. Radar images, void of precipitation as the afternoon began, were covered in less than an hour’s time, with a measle-like array of tiny precipitation “returns”. What’s more, the atmospheric set-up was perfect for cold air funnels. Counterclockwise-twisting eddies of air embedded within a huge, cold reservoir of air above the entire Midwest Tuesday—a condition meteorologists refer to as a vorticity rich environment—helped encourage the growth of rotating t-storms. Cold air funnels dipped from the bases of several of them near Rockford and DeKalb.
Cold air funnels rarely reach the ground, serving more as visual spectacles than threats, but are fascinating to watch.
WGN-TV Chief Meteorologist Tom Skilling and the WGN Weather Center staff provide daily coverage of weather in the Chicago area.
