For the second consecutive afternoon, showers and a few very isolated thunderstorms developed over parts of the Stateline. While the severe weather threat was extremely low in our area, given the cooler, less humid conditions in place, there were some nervous moments in a few communities as brief funnel cloud sightings were reported.
What you see in the image above, captured by Kathy Fender near Seward in Western Winnebago County, is what's called by meteorologists a cold air funnel. These differ from tornadoes in the fact that they're rooted considerably higher in the atmosphere, and can emanate beneath garden variety showers or weak thunderstorms. They're called cold air funnels not because the air at ground level is cold, rather the air aloft is particularly cold.
These funnels, most common in spring and fall, but possible year-round, generally are a by-product of an area of upper level low pressure. That was indeed the case this afternoon, as an upper level low moved slowly through Wisconsin, generating the cold air aloft that spawned the widely scattered showers, and ultimately the brief cold air funnel.
While they can make for some uneasy moments, cold air funnels are very rarely harmful. In fact, rarely do the funnels touch down, and most typically extend just a few hundred feet from the base of the cloud. The rare funnels that do touch down are not candidates to produce significant damage. If any damage does indeed occur, it's almost always on the EF-0 scope, with winds of 85 MPH or less.
As the sun sets this evening, whatever showers that remain will dissipate rapidly, and the entire area will be dry by 9:00pm at the latest. Skies are to clear tonight, with sunshine likely to prevail for most, if not all of our Thursday, along with comfortably cool temperatures in the upper 70s.