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Tornadoes

Mother nature's fury

Created date

June 13th, 2018

Between 1950-2018, National Oceanic and Atmospheric Administration’s Storm Prediction Center tracked and plotted tornadoes in the USA. Color coded by strength: dark blue represents F-0; turquoise F-1; green F-2; yellow F-3; orange F-4; red F-5.

They are amongst the most powerful natural forces on the face of the Earth. Tornadoes have long been at the center of fact and fiction and, understandably, a source of fear and awe.

Many people identify them with the “cyclone” that took Dorothy and Toto in the classic film The Wizard of Oz (1939); but for those who live in the Central-Southern and Mid-Western United States, there is nothing fairytale about them.

On March 18, 1925, for instance, the deadliest single tornado in U.S. history roared across three states, killing an estimated 695 people in Missouri, Indiana, and Illinois. Three quarters of a century later, a tornado in Moore, Okla., touched down with record-breaking 301 mph winds, making it the planet’s strongest twister ever measured.

In some respects, these natural horrors remain a mystery, even in an age of advanced science. Recently, the Tribune spoke with University of Wisconsin atmospheric scientist Dr. Leigh Orf about what they are and what they are capable of.

Tribune: What exactly is a tornado?

Orf: When you’re this immersed in a subject, that’s a difficult question to answer without sounding dull. The simplest and, therefore, the best definition is that a tornado is a funnel that extends from a cloud to the ground and rotates.

Tribune: And where do they generally occur?

Orf: Every single continent on Earth—except for Antarctica—has had a tornado. But they typically show up in the Mid-Western United States, and this has a lot to do with what causes them.

In the U.S., you have the Rocky Mountains to the West and the Gulf of Mexico to the South. Tornadoes normally come from a storm that we call a supercell.

These storms develop when low pressure rapidly builds and brings air masses together, sucking in warm, wet air from regions like the Gulf of Mexico and cold, dry air from places like the Rocky Mountains.

This sharp gradient of dry cold and moist hot airs is a focal point for storms ripe for tornadoes.

Tribune: How do you measure a tornado’s strength?

Orf: It’s a gruesome process. We measure it on a scale of EF0 to EF5 mainly based on how much it destroys.

It’s very important for storm surveyors to do an investigation immediately after a tornado happens and before people clean up so they can assess the damage path.

Tribune: What kind of destruction are they capable of?

Orf: I should start off by saying that only a small percentage of the really big storms produce tornadoes; and only a percentage of that percentage produce the truly damaging ones.

When these do occur, they’re catastrophic. The powerful tornadoes can vaporize a heavy, well-built structure or toss and crush an SUV like it’s an empty soda can.

Tribune: Are we able to predict tornadoes?

Orf: Unfortunately, we generally don’t know where a tornado will drop, and we don’t know where it will go. That’s where the research is pointed.

A tornado’s path can shift on a dime. I’ve seen where the tornado looks like it will take a left turn, and then there’s some type of disruption and its direction reverses.

I don’t think that level of prediction will be in our scope for the next few decades.

Tribune: What is the warning time frame?

Orf: We need to continue to extend our predictive capabilities, but I think the warning time is what it should be, which is about 15 minutes. Our fear is that too much warning time could produce a “cry wolf” effect where people think: “Oh, I have 45 minutes—I can get some groceries before then.”

The problem is that we don’t know with certainty what the tornado’s path will be. If it suddenly shifts direction, a 45-minute warning could turn into a 3-minute warning, and that would be very dangerous.

Tribune: What steps do you recommend a person take in the event of a tornado?

Orf: If you have a basement, go there. For those who don’t have a basement, I would recommend moving to a sturdy, central location on the lowest floor—away from any windows.

Now, if you happen to be in your car, do not attempt to outrun the tornado.

Sheltering under a nearby bridge, for example, is better than nothing. Do not, however, stay in the car.

If you catch a tornado while in your vehicle, Mother Nature will win.


The Enhanced Fujita Scale

EF0 = 65-85 mph (light damage)

EF1 = 86-110 mph (moderate damage)

EF2 = 111-135 mph (considerable damage)

EF3 = 136-165 mph (severe damage)

EF4 = 166-200 mph (devastating damage)

EF5 = 200+ mph (incredible damage)

Originally created by Dr. Theodore Fujita, the Enhanced Fujita Scale uses 3-second wind gust measurements along with on-scene damage assessments to rate the strength of a given tornado.

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