MONTGOMERY, Ala. (WSFA) - Monday may have featured heavy rain and thunderstorms across parts of our area, but what we saw was nothing compared to what hit parts of the Midwest. A powerful and rather rare derecho packing winds upwards of 112 mph rocked more than 770 miles of real estate from the Plains to the Ohio Valley.
The intense wind storm developed in Nebraska during the morning hours and strengthened into a mature derecho as it charged eastward all the way to Michigan, Ohio and Kentucky by the evening hours. It left more than 1 million without electricity, caused extensive damage and had social media buzzing throughout the day.
The damage ranged from significant structural damage to the destruction of acre upon acre of crops like corn and soybeans to cars and trucks being blown over. There are even photos of 2x4 boards piercing the sides of homes.
According to the Storm Prediction Center, there were hundreds of reports of severe wind gusts and wind damage from near Omaha to the Ohio River. A handful of those wind gust reports were dubbed significant, meaning they were at least 75 mph!
While damage and severe wind reports extended nearly 800 miles, the worst of the derecho hit Iowa and northern Illinois. That’s where wind gusts over 75 mph were most frequent.
In fact, there were several wind gust reports over 90 mph, which is very rare to get with severe thunderstorms. For perspective, the 112 mph wind gust in Midway, Iowa, is the same intensity as a very strong EF1 tornado or weak category 3 hurricane!
So, now that we know a derecho charged across the Midwest on Monday, what exactly is one? And what about us here in Alabama -- do we get derechos here? Let’s take a look!
According to the National Weather Service and Storm Prediction Center, a ‘derecho’ is defined as widespread, long-lived wind storm that produced significant damage over a swath of at least 250 miles. Over that path, the line of storms must produce constant wind gusts of at least 58 mph, with pockets of 75+ mph gusts thrown in the mix.
These “lines” of intense thunderstorms can also be referred to as bow echoes, squall lines, quasi-linear convective systems, or mesoscale convective systems. Each of them are technically and scientifically correct.
If you haven’t heard of these intense wind storms before, it’s probably because they don’t occur all that often. Not only that, but they are very rare in Alabama and across the Deep South.
They aren’t unheard of, though. One of the more memorable derechos to impact Alabama happened just two years ago on June 28th, 2018. That derecho impacted the entire state from Huntsville and Muscle Shoals to Birmingham and Tuscaloosa to Montgomery to Dothan and Mobile. Widespread strong to severe wind gusts occurred along its path, leading to damage and power outages statewide.
Again, they aren’t necessarily unheard of here in Alabama, but they are certainly considered unusual and very rare. On average, Alabama is impacted by a derecho one time every 2-4 years. The northern half of the state is more at-risk and susceptible to being hit by a derecho than locations south of U.S. 80 and I-85.
The Plains, Mississippi River Valley, Midwest, and Ohio River Valley are where it’s most common to get derechos. That’s where the ingredients for their formation and maturation are typically in place.
So when do these derechos happen?
About 80% of all U.S. derechos happen during the months of April, May, June, July, and August. More than 60% happen just during the months of May, June and July. That’s because these wind storms need big-time heat, humidity and “energy” (referred to as CAPE). The late spring and first half of summer are usually when these ingredients all come together.
There are more factors and variables that go into forecasting and predicting derecho formation, and you can read about them and so much more by clicking on the links scattered about this article.
So now you know what a derecho is! And while we may not see one in Alabama for years, they can happen and have the ability to be one of the most destructive weather phenomena Mother Nature can throw at us.