Cold Air Funnel
Today the NWS Milwaukee confirmed that an EF-0 tornado occurred in SW Waukesha county Tuesday evening. The winds were estimated around 80 mph, and it only traveled 0.7 miles. That was the 3rd tornado that was confirmed in our area from that night. While the severe weather has passed, take a look at this picture from my CBS58 Storm Spotter Tom Purdy.
This is a cold air funnel. They can occur in the wake of a strong cold front. You need cold air aloft, some surface heating, and wind shear to make one of these guys. We had all of those necessary ingredients this afternoon to form the funnel.
Most of the time these cold air funnels don't reach the ground because they're attached to a high base cumulus cloud. Every now and then they can reach the ground and kick up some stronger winds. Sometimes these weak tornadoes can produce damage, much like a strong dust devil.
As the Lake Michigan surface waters continue to warm, we will see more waterspout opportunities through the month of September.