Known as a “derecho“, these events are indeed uncommon, but have always been around: the term was originally coined in 1888 in a study of thunderstorm wind damage which occurred in 1877.
In fact, one of the most famous events occurred when global temperatures reached a minimum, back in the 1970′s. Known simply as “The Storm”, it occurred 35 years ago today, on July 4, 1977. There were widespread blowdowns of trees (see the photo, above). Even though the event occurred over relatively unpopulated areas in Minnesota, Wisconsin, and Michigan, the highest recorded wind speed was an astonishing 115 mph, officially recorded with an airport anemometer.
Compare that to the derecho event of last week, which occurred over heavily populated areas: the highest measured wind speed in the extensive list of reports at the Storms Prediction Center was only 92 mph, and even that was on a home weather station, and so is unofficial.
So, why all the fuss over last weeks storm? Because it didn’t hit flyover country. Tens of millions of people were affected, and millions went without power.
Of course, those affected included many journalists, so it is only natural that they would speculate (and seek out experts to speculate) about the sinister causes of such an event.
Surely the silliest comment I saw came from Bill Nye, “The Science Guy”, who stated: “…We had a 30-degree temperature drop in Maryland and Virginia this weekend, in just – in a half-hour. These are consistent with climate models.”
First of all, such temperature drops occur routinely with the passage of mid-latitude thunderstorms. Secondly, climate models predict no such thing anyway. If “The Science Guy” gets it this wrong, how can I trust him on anything else?