Weather Terminology: What Is a Derecho?

Yesterday, a well-organized complex of storms brought widespread and significant wind damage to many across the Midwest, including the Stateline area. Now, this wasn't just your typical wind storm. In fact, there's a certain term that meteorologists give to a wind storm that is widespread and long-lived, and that is a "Derecho". 

Derecho is actually a Spanish derived word meaning "straight" or "direct". Derechos develop in an environment with very warm and moist air at the surface, colder air aloft, and moderate strong winds in the upper-levels of the atmosphere. They also tend to navigate where the highest amount of CAPE or atmospheric energy resides. Now, there are certain qualifications that a storm event has to "reach" in order to be classified as one. To start, the damage path from this complex of storms has to exceed at least 240 miles. And in that damage path, winds gust have to be consistently gusting at or above 58 mph. 

Yesterday's derecho in particular started out in southeastern South Dakota, ending it's path of destruction in western Ohio. If I did the math correctly, that is a path that stretches nearly 770 miles, leaving plenty of damage and many without power in it's wake. In fact, Iowa received the worst of this event, as multiple reports came in of wind gusts exceeding 90, even 100 mph.  Midway, IA came in with the highest wind gust from yesterday's event thus far with a gust of 112 mph. Pictures of the aftermath showed cornfields  were flattened, and silos completely destroyed. Although at a somewhat weaker state, most of the wind gusts observed here at home were between 70 to 80 mph. Despite the coverage and intensity of the wind damage, there were no fatalities from the storms reported thus far.

This begs the question. How often does the Stateline experience a derecho? According to climatology provided by The Storm Prediction Center, our region sees one derecho every year. Whereas areas to the south, including portions Oklahoma, Arkansas, and Missouri, see about 4 derechos every 3 years. So, not as often as other spots across the United States. However, the result remains the same, as the impacts from these intense storm systems can last a long time.