Twelve hundred times a year, on average, a tornado touches down in the U.S. The twisting storms can leave behind a wake of splintered houses and uprooted trees—and claim the lives of anyone caught in their paths.
Tornadoes can strike at any time or place, although they’re most common from March through June and in the central U.S. Unfortunately, scientists still don’t understand exactly how they form.
Harold Brooks, a research meteorologist at the National Severe Storms Laboratory in Oklahoma , is trying to unravel the mystery. He uses computer models to study the conditions under which tornadoes form, how the storms behave, and their impact on people. Brooks has also worked on finding better ways to forecast tornadoes. He even served as a technical adviser for the 1996 movie Twister. His latest study reveals a big change in tornado activity over the past few decades. Depending on how you look at it, the news could be either encouraging or terrifying.
Science World: Why did you decide to study tornadoes?
Harold Brooks: They’re one of the most fascinating things on the planet. It’s amazing to think that the same physical processes that create everyday wind and clouds also create tornadoes, causing things to happen that wouldn’t ordinarily happen. I love this example told to me by a friend: In 1957, a woman in Dallas, Texas, looked outside and saw a railroad car going down the tracks. That’s not so unusual, right? Well, this one was going end over end!
What inspired your new study of tornado activity?
Harold Brooks: April 2011 had the most tornadoes of any April in U.S. history. Then the beginning of 2012 had the most tornadoes for the early part of a year than any other in U.S. history. Reporters started asking us, “Are tornadoes happening earlier in the year? Are they getting worse?†So we decided to study the official tornado records, which go back 60 years.
What did you find?
Harold Brooks:We found that tornado occurrence has become more variable. Half of the recordsetters for the most tornadoes in a given month, and half of the recordsetters for the fewest tornadoes in a given month happened in the past 12 years. Additionally, all of the tornado seasons with the earliest starts and all of the tornado seasons with the latest starts happened in the past 15 to 20 years. Lastly, the number of days with tornadoes has dropped, but the number of days with 30 or more tornadoes has risen. So when people ask, “Are we going to get more tornadoes or fewer tornadoes?†the answer is, “Both.†The next steps are to figure out: Why? And will higher tornado variability make a difference in terms of damage, death toll, and rebuilding efforts?
What’s your favorite part of your job?
Harold Brooks: Learning something new and then telling someone else about it. For instance, the first time the results from the tornado variability study came up on the computer screen, I knew something that no one else on the planet knew. The first thing I did was show it to a couple of co-workers. Then I thought about how I would explain the results in a way the public would understand.
Why is it important to study tornadoes?
Harold Brooks: Every year in the U.S., tornadoes cause 50 to 60 fatalities and billions of dollars worth of damage. If we can find ways to reduce those numbers and improve our response, that’s a good thing. Also, as we learn more about tornadoes, we improve our understanding of other threats in the atmosphere, like hail, winds, and heavy rain. It’s all part of understanding how the occasionally violent atmosphere works.
(This article first appeared in Science World Magazine)