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A picture of a woman woman carrying her child through the rubble of the Oklahoma tornado

A woman carries her child past a destroyed elementary school in Moore, Oklahoma.

Photograph by Sue Ogrocki, AP Photo  

Ker Than

for National Geographic

Published May 21, 2013

A massive tornado that tore through the Oklahoma City suburb of Moore on Monday and killed scores of people was unusual not for its size or ferocity, but for the path it took, experts say.

"Strong tornadoes occur pretty much every year," said Christopher Karstens, a research scientist with the National Severe Storms Laboratory (NSSL) in Norman, Oklahoma. "But most of them occur out in open flat areas, or areas where there aren't many people. It's rare that we get one of these going through a major populated area."

Scientists estimate that the devastating twister was half a mile (0.8 kilometers) wide and generated winds of up to 200 miles per hour (320 kilometers per hour).

During its 40-minute tour of destruction, Monday's tornado carved a 20-mile path through Newcastle, Moore, and South Oklahoma City, reducing entire neighborhoods and at least one elementary school to rubble. The official death toll on Tuesday morning stood in the 20s.

According to the National Weather Service, Monday's tornado was an EF5 on the enhanced Fujita scale—the most powerful type of twister.

"This is absolute devastation like nothing I've ever seen before," Betsy Randolph, with Oklahoma State Police, told Fox 25.

"This may be worse than the May 3, 1999, tornado," said Randolph, referring to a similarly strong tornado that affected some of the same communities.

Tornado Alley

Oklahoma City lies within an area of the Great Plains known as Tornado Alley, a region that stretches from South Dakota to central Texas and is particularly vulnerable to tornadoes.

Tornado Alley occupies a unique geographic position where warm moist air from the Gulf of Mexico and cool dry air from the Continental Polar Mass in Canada meet, explained NSSL's Karstens.

"In the springtime, those air masses tend to work together to create environments that we saw [on Monday]," he added.

While the United States has perhaps the best historical records for tornadoes, twisters also occur elsewhere, including in Italy, India, and South America. (See photos of extreme weather.)

What Tornadoes Have in Common

While tornadoes can differ in their size, strength, and location, they all share certain characteristics. They are spawned from a type of rotating storm called a supercell thunderstorm.

And they are all driven by atmospheric instability and by a phenomenon known as wind shear. This happens when "wind near the ground blows in one direction, but aloft it blows in another direction. This creates shear in the airflow," Karstens explained. "If you produce an updraft within that flow, the updraft will acquire the properties of the air, and the atmosphere begins to spin and rotate."

While scientists understand some of the basic setup conditions necessary for tornado formation, there are still many fundamental questions about tornadoes that remain unanswered.

Tim Samaras, a tornado chaser known for for getting instruments inside tornadoes to measure pressure and wind speeds, says we have a lot to learn about how tornadoes form.

"We still don't know why some thunderstorms create tornadoes while others don't," he said. "We're trying to collect as many observations as possible, both from outside and from the inside [of tornadoes]." (Related: "A Tornado Chaser Talks About His Science and Craft.")

Scientists also have a limited understanding about how tornadoes maintain their intensities and what causes them to fizzle out, Karstens said.

Tornado Forecasting

At the moment, tornadoes are much more difficult to forecast than hurricanes. For example, the National Hurricane Center was able to predict the path of last year's Hurricane Sandy with startling accuracy a full five days before it made landfall.

In contrast, residents of Moore had only 16 minutes after the first warning before the tornado touched down.

Part of the difficulty, Karstens said, is that tornadoes are much smaller than hurricanes.

"It's really a matter of scale," he explained. "With the hurricane being so large, we're able to populate our models with lots of points to resolve it and we can come up with much more accurate multiday forecasts."

Karstens is involved in an NSSL project that aims to predict a tornado's path shortly after it forms, called Warn-on-Forecast.

He's optimistic that tornado forecasting will improve as computers and tornado modeling software become more powerful, and as more environmental data such as temperature and dew point measurements are gathered close to tornado-spawning storms by instruments and tornado chasers.

"We've got a long way to go," he said, "but I think we're making steady progress."

Jane J. Lee contributed reporting to this article.

5 comments
Robert Balderrama
Robert Balderrama

   MY VISION TO REDUCE THE FORCE OF A TORNADO OF ANY SIZE.

I believe that global warming is causing this problem with more tornadoes, much bigger and alot stronger then when I was young. We as humans on this planet have to create ways to protect us and all animals and plants for our future to survive. We cannot continue to standby and watch these monster tornadoes create havoc on our planet. right now all we do is Track ,Warn , and Hide for protection. The reason I wrote this message on National Geographic Blog is my hope that any scientist that is working with some Weather Research program to learn more about tornadoes. might be reading this and apply my vision into reality. If you are out there PLEASE  keep reading for the sake of saving lives.

I think air delivery is the way to reduce the rotation of the tornado, the Germans made   The Shockwave Vortex Gun or Wind

Cannon to shoot down the enemy bombers in world war2, We could create advanced technologies with that and with all the

weather advancements in predictions. A formula can be made and used along with The Shockwave Vortex Gun or Wind Cannon

. research in a miniature controlled format to create the formulas for the right amount of air or wind for the Wind Cannon to stop or

reduce the speed rotation, that are needed for each and different tornados.If you put Wind Cannon on google images you can see

a couple of old pictures of the Wind Cannon,they are probably old German war pictures. I have seen science shows on tv where

miniature tornadoes were produced to study them, create a miniature Wind Cannon, that would be the size equal to the ratio of the

miniature tornado and the ratio to a real tornado and real Wind Cannon.this is how formulas can be created. the size of the Wind

Cannon in the picture I seen there is someone standing next to it and he looks small compared to the Wind Cannon. I know if

some research were done with the Wind Cannon that we always seem to make advancements in size to efficiency,We  just need

to start the research.I hope to hear back and maybe you can help get the research going.I am not interested in anything but to help

mankind in our future of global warming and the destruction it is creating.

Thank You

Concerned Human

Azrael Exael
Azrael Exael

Scientist keep warning us that because global warming, we are going to have fewer but much stronger storms, last year was the Cyclone over Yew York City, yesterday over Oklahoma. Unfortunately no one is listening and more and more people are going to die because of the Federal Government and many people are completely dismissing what scientists are saying. A friend of mine truly believes the bull that the media is saying, “there is not enough data to know this for certain, man has been on the planet for a very short time to know what the planet is doing”. Well I for one believe scientist and I am sure that they are right, if people pay attention they will find out that each storm is killing more and more people.

Vedat Şafak Yamı
Vedat Şafak Yamı

I am in Turkey and I feel deep sorrow for those injured and those who lost their lives in this catastrophe..

Jan Jensen
Jan Jensen

@Azrael Exael  and @Robert Balderrama 

These storms have always occurred.  They seem more horrific because you see them strike densely populate areas unlike the days when many hit some fields, or wiped out some farm houses and trailers.  Imagine the toll The Great Natchez tornado  (which killed hundreds) would have were it to occur today. The global warming theory is full of holes, THAT is why no one is listening.

See the question "Q: Is it just my imagination or are tornadoes becoming more prevalent each year and if so, why?" at link below

http://usatoday30.usatoday.com/weather/resources/askjack/watorhty.htm

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