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Tornado-Chasing Project Aims to Improve Forecasts
The technology available this time is far superior. The inaugural Vortex used Doppler radar on planes, which would pass over a tornado at about five-minute intervals. Now radar mounted on trucks, which can get within two miles of a tornado, will provide uninterrupted data.
"We will be able to distinguish between rain, hail, dust, debris, flying cows," said Howard Bluestein, a meteorology professor at the University of Oklahoma and member of the Vortex2 steering committee.
Two ingredients are necessary to form the supercell thunderstorms that spawn tornadoes: a source of buoyant energy, namely warm and moist air near the ground, and a rotational force generated by winds at the surface blowing at a different speed or direction than winds high in the atmosphere.
A typical thundercloud develops as warm air rises into colder air masses above, then usually dissipates quickly once rain falls. Supercell thunderstorms, by contrast, can last for hours and can move rapidly, tracking over 100 miles. Supercell thunderstorms may also create "mesocyclones," swirling winds embedded within the larger thunderhead that can be as much as six miles in diameter.
About five to 10 percent of these storms actually spin off tornadoes, which are typically about 500 feet in diameter. Scientists know what forms a mesocyclone, but they are largely lost when it comes to understanding which ones will spawn tornadoes and how violent they will be.
"A number of things have to happen sequentially and at the same time and in the right order," said John Monteverdi, a meteorologist at San Francisco State University who has been chasing tornadoes for 24 years. "You have to start knocking the dominos down to find out what happens in that last stage. I think we're getting close, and this project should help."
Risky though it appears, members of the project note that their crews have never logged a death or severe injury. But they say amateur tornado-chasers who follow scientists around with video cameras are endangering themselves and others. Not only do these adrenalin junkies put themselves in harm's way, the scientists say, they often speed and park their cars in the middle of the road, endangering other motorists and distracting highway patrol officers.
Scientists warn that it is only a matter of time before a major tornado sweeps through a densely populated urban area and causes horrific damage and loss of life.
Chicago, Atlanta, Dallas and Houston, in particular, are in regions prone to violent tornadoes. Wurman said in a 2007 study that a tornado cutting through Chicago could kill 13,000 to 45,000 people and cause tens of billions of dollars in damage.
"Tornadoes have a great beauty to them sometimes," Wurman said. "There's a great elegance to the vortex itself. But when you see it going toward a town or city, there's a quick change in your impression, and it's like a tiger: Something beautiful becomes deadly."