Weird Weather Map Cloud = Monarchs

Posted Oct. 2nd, 2014 by Melynda Harrison

A weird cloud appeared on weather maps earlier this month causing forecasters to scratch their heads.

It was a large, slow moving cloud that changed shapes as it drifted south over the U.S. Midwest.

A screenshot taken by NWS meteorologists, capturing the odd radar reflectivity that appeared east of St. Louis, Mo. (NWS St. Louis via Facebook)

A screenshot taken by NWS meteorologists, capturing the odd radar reflectivity that appeared east of St. Louis, Mo. (NWS St. Louis via Facebook)

A freak storm? Nope. It was millions of monarch butterflies traveling from Canada to Mexico, a migration of 3,000 miles for some individuals. Monarch numbers have been declining lately, and had their lowest numbers in 2013,  but may be seeing a resurgence in 2014.

“Keen observers of our radar data probably noticed some fairly high returns moving south over southern Illinois and central Missouri,” the NWS said. “We think these targets are Monarch butterflies. A Monarch in flight would look oblate to the radar, and flapping wings would account for the changing shape!”

According to the U.S. Fish and Wildlife Service,  “[The monarch migration] has become more dangerous and less successful for many because of deforestation, illegal logging, increased development, agricultural expansion, livestock raising, forest fires, and other threats to their migratory paths and summer and overwintering habitats.”

Monarchs like these fooled weather watchers into thinking a storm was headed their way.

Monarchs like these fooled weather watchers into thinking a storm was headed their way.

Does the cloud of monarchs mean the species is making a recovery? Unfortunately, probably not.

The Washington Post reported, “From the radar echoes, it might seem as if there was quite a swarm of butterflies heading south on Friday. However, it doesn’t take much for the radar to light up when it’s dry out. ‘In dry conditions, the radar is very sensitive to something like insects,’ Laura Kanofsky, a meteorologist for the National Weather Service in St. Louis. ‘It doesn’t take a whole lot of insects to create a high return.’”

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