Tom Johnstone: The Xenia tornado was the strongest tornado in what has been referred to, and continues to be referred to, as the Super Outbreak of April 3, 1974.
The tornado was on the ground around 16 miles. It was a half mile wide. And in that half mile, there were multiple city blocks that were pretty much wiped away, with maximum speeds pretty close to 200 miles an hour, more likely in the 150 to 175 mile an hour range.
I think four schools were destroyed. Hundreds of homes, churches, everything.
It was a catastrophic, large, violent tornado.
Mike Frazier: In layman's terms, what were the atmospheric conditions that allowed meteorologists to foresee the possibility of tornadic activity that day?
Johnstone: So for any thunderstorm to form, you need a few ingredients.
You need to have something to cause air to lift, like a front or a trough or a low pressure system. You need to have buoyancy or what we refer to as atmospheric instability. You need to have the tendency for when air is pushed upwards, it doesn't slow down, it continues to accelerate and rise. And that's what really gives way to the thunderstorms.
"What we lacked in 1974 was the degree and the accuracy of computer models that we have today."
And the final ingredient and what was in place in so much abundance on April 3, 1974 is wind shear.
When meteorologists talk about wind shear, we talk about winds which change direction as you go up in the atmosphere, but also increase dramatically in speed. So on that day, all the parameters we look at for severe weather were off the charts.
Plenty of instability, a very strong cold front and an active warm front that came through Dayton, Xenia, Cincinnati during the morning.
Frazier: Now, when those conditions are present or in the forecast, that's no guarantee of tornadoes or severe storms.
Johnstone: We have plenty of days where the ingredients are mostly in place, but for whatever reason, thunderstorms don't get triggered. So everything has to come together at just the right time and place. So we talk a lot about conditions being favorable, but it doesn't mean that the conditions are going to happen.
Frazier: Compare severe weather forecasting today to the way it was 50 years ago in terms of the National Weather Service's ability to forecast severe weather.
Johnstone: Well, 50 years ago, we had a lot of the things we have in place today. What we lacked in 1974 was the degree and the accuracy of computer models that we have today.
So our ability to simulate what the atmosphere is going to do over the last 50 years has made amazing jumps in terms of speed and accuracy of those predictions.
Frazier: The two tornado outbreaks that Ohio had, that we had in the northern parts of your forecast area in west central Ohio and northern Miami Valley, is that unusual to have two tornado outbreaks already so early in the season?
Johnstone: It definitely is unusual. Not so much the March, but February wintertime tornadoes in the Miami Valley in southwest Ohio have historically been pretty rare. What we've seen is a pronounced change going back, even to 1974.
We've seen a couple of interesting things have happened with tornado trends since 1974. We've also seen a shift in the most frequently visited areas with tornadoes away from Oklahoma, Kansas, Texas, the traditional tornado alley, to more of a Mid-South, Alabama, Western Kentucky, Tennessee, and slowly impinging on the Ohio Valley.
Frazier: What can people do to keep themselves safe from severe weather?
Johnstone: So you've got to have a safe place to go to and be able to get there in a hurry.
So for most homes, a frame home, if you have a basement, that's the place to go. If you have a reinforced storm shelter, which more and more people do, that's the place to go.
If you can't get underground, get to the lowest level of your home. Get as many walls as you can between you and the outside. You don't want to have a window in the room.
Some people will get in their bathtubs. But if their bathroom has a window right above the bathtub, that's probably not the best place either. So a closet and interior room on the lowest level of your home or business is going to be the next best place, and it's going to allow you to survive 99.5% of all tornadoes.
Where we get into issues with people dying are mobile homes. Recall the tragic fatalities in Logan County recently were all in mobile homes. Mobile homes are not safe structures for tornadoes or severe thunderstorms really.
Frazier: And how can people stay in touch with the latest weather information?
Johnstone: We recommend folks have multiple ways to get warnings. So TV and radio are always going to be great ways to get warnings.
Make sure your cell phone - make sure you don't deactivate the wireless emergency alert warnings so that if you're not paying attention to the weather, your cell phone could be your last line of defense - lets you know, ‘Hey, there's a tornado warning issued for my area.’
And we always recommend folks invest in a weather radio - it’s your smoke detector for weather.
