What the heck? I always consi-dered myself to be fairly well read. I’m fasci-nated by words and I pay attention to weather. I have Weath-erbug installed on my computer and I frequently have the Weather Channel on TV during weather events. Of course, I’ve always known about tornadoes and hurricanes and tsunamis and cyclones and other severe weather phenomena.
But I don’t remember ever hearing the term derecho until this year, although I gather they’ve been around forever and in fact, the U.S. experienced an especially terrible one in 2012. It mostly hit the mid-Atlantic states and resulted in the highest winds ever recorded in June or July. Twenty-two people died and over five million lost power. Did they call it a derecho? If they did, I must not have picked up on it.
Derecho is Spanish for “straight.” A derecho is rather like a tornado but with straight line winds instead of the circular motion of winds in a funnel cloud. (In case you didn’t know, tornado is the Spanish word for “turning.”)
To technically qualify as a derecho, the Weather Service criteria dictates that the line of damage must be at 240 miles long with wind gusts up to at least 58 miles per hour. Actually, many of them are much worse than that. In the one Indiana experienced a couple of weeks ago, Wabash was the hardest hit with 100-mile-an-hour winds. In spite of that, there was a surprisingly small amount of damage except for uprooted trees and ripped off branches. I lost power for approximately 10 hours. In 1998, a derecho that hit Michigan resulted in recorded wind speeds of 130 miles an hour.
Here is how the Storm Prediction Center defines a derecho: “Derechos are associated with bands of showers or thunderstorms that assume a curved or bowed shape. The bow-shaped storms are called bow echoes. Derecho winds are the product of what meteorologists call downbursts. A downburst is a concentrated area of strong wind produced by a convective downdraft (i.e. areas of downward moving wind that are smaller and more intense than other downdrafts).” So, now you know.