Massive wave of butterflies lights up Denver weather radar

10:13am PDT - October 5th, 2017    weather radar - ABC News

A lacy, cloud-like pattern drifting across a Denver-area radar screen turned out to be a 70-mile-wide (110-kilometer) wave of butterflies, forecasters say. Paul Schlatter of the National Weather Service said he first thought flocks of birds were making the pa…