What Is A Derecho And Why Are They So Dangerous?

May 2024 · 1 minute read

What causes a derecho, according to NOAA, are downbursts. Downbursts happen when wet humid thunderstorms interact with drier air, causing the atmospheric thunderstorm moisture to evaporate. The surrounding air then cools while increasing in density. Because of that density, the air gets pushed down toward the ground and causes strong winds, called downbursts. By doing so, even more dry air gets sucked into the hot and humid thunderstorm system, as the downbursts strengthen and sometimes cluster — stronger downbursts equal stronger winds, and it all travels in one direction in a united front.

Like what happened in the 2023 Midwest derecho, something called a bow echo can form — a gang of powerful thunderstorms that all travel in one single direction in an arced formation. Long-lasting bow echos or a series of bow echos all grouped together become derechos. Satellites help predict the path derechos take, and the earliest derecho known to science is thought to have been observed by University of Iowa physics professor Dr. Gustavus Hinrichs, who coined the term in the 1880s. A Hinrichs paper published in the American Meteorological Journal in 1888 seems to describe a derecho crossing the Iowa plains in 1877.  Meanwhile, Derechos also sometimes happen in the American Northeast.

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