Today’s Ask Storm Team 11 question comes from Lenny Beetz. He asks, “What is a derecho?”.
Derechos are long-lived, powerful straight line wind storms. Derecho is a Spanish word meaning “straight ahead” or “direct”. In order for a storm system to qualify as a derecho, two classifications need to be met. The first is that wind gusts within the storm need to exceed 57 mph. Second, the swatch of damage has to be at least 240 miles.
One can think of a derecho as a cluster of downbursts. Recall a downbursts is when a strong surge of air from the storm hits the ground and spreads strong winds in all directions.
In order to get a derecho to form, we first need a moist environement for scattered storms to form. When the back side winds become stronger than the front side winds, a bowing effect occurs in the line of storms. This is called a “bow echo”. Usually the strongest of the winds are within the bow echo.
These damaging winds can travel over hundreds of miles and cause significant damage.
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