A mysterious butterfly-shaped cloud spotted over St. Louis last week was built from actual butterflies, the National Weather Service said. In a rare coincidence, a giant swarm of migrating monarch butterflies resembled a butterfly on radar for a short time Friday afternoon (Sept. 19). Forecasters suspect hundreds of monarchs were flying between 5,000 feet and 6,000 feet (1,525 meters to 1,825 meters) above the ground, heading south to Mexico. Though small, their fluttering wings are good radar targets, the National Weather Service (NWS) said on Facebook. No one saw the butterflies, but the radar signals suggest the "targets" were flapping, flat and biological, similar to a monarch. Hummingbirds are migrating now as well, but the zippy birds prefer to fly at treetop level, ruling out a Hitchcock-like scenario, according to the NWS. The double-butterfly is not the first time a radar image mirrored its maker. In 2011, a startled flock of blackbirds in Beebe, Arkansas, looked like a bird's head and beak. A strange radar image that puzzled forecasters in Huntsville, Alabama, in June 2013, turned out to be reflective particles used to test military radar. More via livescience.
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