Denver radar detects a massive cluster of butterflies

Denver radar detects a massive cluster of butterflies

We all know that radar can detect rain, hail, snow, sleet, and even tornadoes.

But did you know that it can detect butterflies as well?

On Tuesday, Oct. 3, a National Weather Service meteorologist in Boulder, Colorado was monitoring the radar when he noticed a strange pattern near Denver showing up on his screen.

It was a dry day and there was no precipitation in the area.  His first thought was the radar was picking up a 70-mile wild swath of birds, which radars often detect.

A very similar situation happened here in the Mid-South several months ago when our First Alert Doppler radar detected a strange return over eastern Arkansas on what was a clear evening.  It was confirmed by people near the anomaly to be a very large flock of geese.

The Denver meteorologist put out a request for confirmation on social media. It wasn't until the next day that he got an answer. It was a large cluster of painted lady butterflies.

They look very similar to monarch butterflies and are frequently detected on radars in the Midwest.  It is believed that flowers in full bloom along Denver's front range attracted the butterflies.

They have also been reported in large numbers in other parts of Colorado and as far north as the Dakotas.

Research suggests the butterflies migrate southwest during the fall when wildflowers are plentiful and in full bloom.

That is also the time that the butterfly populations surge, thus making them more likely to be detected on radar.

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