by Matthew Cobb
The US National Weather Service Weather Forecast Office (you could work on the title, folks!) reports that on Friday evening, shortly after sunset, their radar picked up some unusual signals in Wisconsin, near Milwaukee (insert beer joke here). Although some of these blobs may have been snow flurries, the Weather Service suggests that these are more likely to have been migrating birds. The site adds:
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.
YouTube has this rather cool video showing
“nocturnal migrating birds, bats, and insects in the continental U.S. from sunset to sunrise Oct. 1, 2008. The blocky green, yellow, and red patterns, especially visible on the east coast, represent precipitation; but within an hour after sunset, radar picks up biological activity, as seen in the widening blue and green circles spreading from the east across the country. The birds, bats, and insects take off, fly past, and get sampled by the radar beam. Note, the black areas on the map do not represent places without birds, necessarily, but rather places where radar does not sample.”
If you want to understand the physics of it all, read this.
h/t @JacquelynGill on Twitter, who also tweeted: “A mass migration of birds is not unusual, as yesterday saw the cessation of southern winds that had made migration conditions unfavorable.”