Updated 3:21 p.m. ET. CHICAGO An unusually massive line of storms packing hail, lightning and tree-toppling winds Wednesday could affect more than one in five Americans as it rolls from Iowa to Maryland. Storm system threatening millions in Midwest could spawn feared derecho.
derecho (n.): a large cluster of thunderstorms that produces widespread wind damage.
Here we are again. About a year ago, a historic derecho tore across the Mid-Atlantic U.S., producing the highest wind gusts ever recorded in the months of June or July. Some 5 million people lost power and 22 lost their lives. The storm also hit major metropolitan areas—meaning that it got a lot more attention from the media and general public than derechos in years past. This week, weather reports indicated that another derecho could be upon us. So what, exactly, does that word mean and where does it come from?
First, it’s pronounced deh-REY-choh. The word means straight in Spanish, a reference to the long lines of wind damage the storms can leave behind. By definition, if the wind damage is at least 240 miles long and gusts are at least 58 mph, the storm is a derecho. But the summer squalls can be even more severe than that, with winds topping 100 mph; a derecho that hit Michigan in 1998 had winds blowing at 130 mph.
As of Thursday morning, no derecho had materialized, but there were still severe thunderstorm warnings for the Mid-Atlantic and beyond. And as a Washington Post writer argued, the bottom line is that a big storm is brewing; people should try to be prepared, regardless of what it’s called.