Weather radar detected a 70-mile-wide swarm of what in Colorado?

Answer: Butterflies.

by / October 10, 2017
National Weather Service

It is not unusual for a weather radar to pick up on things in the air besides the actual weather. All kinds of animals have appeared on radar over the years, and swarms of migrating birds are common. So that was the assumption meteorologists at the National Weather Service made early this week in Colorado when they detected a huge swarm of something flying near Denver.

However, when meteorologist Paul Schlatter posted an image on social media and asked birdwatchers if they could identify the kind of bird forming the swarm, it didn’t take long for people in the area to reply that they were seeing a huge swarm of not birds, but butterflies.

The butterflies were identified as painted ladies, similar in appearance to the well-known monarch butterfly. Apparently, they have been massing in “clouds” along Colorado’s Front Range over the past few weeks to feed on flowers. It’s probably safe to say that the National Weather Service will not be predicting any rain or snowfall from these particular clouds.