However, unlike tornadoes, derechos are a type of straight-line wind. Tornado winds, on the other hand, swirl around.
The word derecho derives from the Spanish language.
While a straight-line wind can mean any wind coming from one direction and going in the opposite direction, derechos most commonly refer to very strong straight-line winds.
In fact, wind damage from derechos is sometimes mistaken to be tornado damage.
What Exactly Are Derechos?
So far, you know derechos refer to strong, straight-line winds. But they’re really much more than just that.
Let’s look at some of the minimal attributes of what makes a true derecho:
- The storm’s winds must generally be at least 58 miles-per-hour
- The derecho should have a life span of at least 6 hours
- Derechos must form in a ‘family of downburst clusters’
- The line of storms producing microbursts and downbursts are long — often 250 miles or even longer
- Winds in some derechos can gust well over 100 miles-per-hour
Derechos come from very strong storms that cover a wide area and travel a long way.
In fact, some of the most damaging derechos have marched hundreds of miles across the country.
Derechos are most commonly found in squall lines. A squall line is a line or row of storms — often fierce — which can extend hundreds of miles long. Despite their length, most squall lines are relatively narrow.
You can easily ‘see’ these bow-shaped areas of these storms when satellite or radar images are superimposed on a weather map.
3 Kinds Of Derechos
Derechos are classified in 3 different ways. Check out how these different types of derechos are defined:
- Serial Derechos: Are found in long squall lines and can involve the formation of many bow echos. Serial derechos form as a result of what meteorologists call migrating areas of low pressure.
- Proressive Derechos: Occur in rather short squall line systems (under 250 miles long) and are associated with stationary fronts. A progressive derecho can involve either one or several bow echos.
- Hybrid Derechos: Involve general characteristics of both serial derechos and progressive derechos.
Historic Derecho Events
Like tornadoes, hurricanes, and other severe wind events, some derechos have reached historic proportions.
Here’s a brief overview of some of the most serious derechos in United States history:
- In 1993, a strong derecho occurred during the Storm of the Century. This derecho produced highly damaging winds that affected Florida and Cuba.
- A very severe derecho affected much of the northern Midwest in 1983 during an event since dubbed the I-94 Derecho.
- The More Trees Down derecho cut a large swath across the country on July 4 and 5 1980. The derecho formed near Omaha Nebraska and finally dying out over Maryland, Delaware, and Virginia. 6 people were killed in this derecho.
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