Funnel clouds occurred over parts of northern Illinois Thursday evening outside of Sublette and Paw Paw, IL (Lee County) along an old frontal boundary that stalled south the Stateline. The combination of a lake breeze boundary moving inland from Lake Michigan, along with high amounts of moisture along I-88, caused cumulus clouds to grow in height, producing a few isolated showers across DeKalb and Lee counties.
Converging winds along both boundaries caused enough spin to occur within the rising clouds to produce brief funnel clouds. In the photo above, two funnel clouds were spotted right next to each other outside of Sublette, IL.
These types of funnel clouds rarely reach the ground, only protruding from the base of the clouds for a short time, and may spin like a top before dissipating. The atmospheric conditions that these funnels develop in are not supportive of strong, damaging tornadoes. The threat for funnel clouds will quickly come to an end once the sun sets, losing the daytime heating.