A lacy, cloud-like pattern drifted across a Denver-area radar screen. It turned out to be a wave of butterflies. It was 70 miles wide. That's according to forecasters.
Paul Schlatter works for the National Weather Service. He said he first thought flocks of birds were making the pattern he saw on the radar Tuesday. But the cloud was headed northwest with the wind. Migrating birds would be southbound in October.
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