Shortly after sunset Friday evening several unexpected radar returns appeared over southern Wisconsin. While there may have been a few flurries lingering across the area, these particular radar returns were too strong to indicate flurries. Also, unlike typical meteorological returns, the radar returns dispersed with time.
The radar was actually seeing flocks of migrating birds. Weather observer Steve Skalecki noticed an unusual flocking of Canadian geese around this time period near Bay View. As Steve described it, "the honking of geese was loud and almost continuous." According to the Wisconsin DNR, "Geese, like most of our migratory birds, often migrate during the night." Moreover, an impressive 100,000 to 200,000 geese stop to refuel and rest at Horicon Marsh each fall before continuing on their journey southward.
The loop below shows the local radar image from 4:53 pm through 5:41 pm. Notice, the strong returns that appear at 5:02 pm and how they spread out and diminish with time. Click the loop for a larger version.