The chances of a Nebraska tornado looked promising.
So the first Saturday of this month, as tens of thousands of Berkshire Hathaway faithful gathered in Omaha to hear Warren Buffett speak, a platoon of tornado researchers piled into tricked-out vehicles and rolled east from their weather laboratory at the foot of the Rocky Mountains.
The convoy would travel more than 500 miles to northeast Nebraska in search of a storm that the scientists hoped would give them a chance to record the deadliest minutes of a tornado.
The crew of about 30 researchers and staff is spending nearly seven weeks traveling the Plains in search of tornadoes. The researchers are undertaking the most ambitious effort ever to understand exactly how tornadoes cause damage. Their workhorses are mobile radar trucks, which will scan intimate pictures of a storm's structure, and a fleet of unmanned tornado pods that will be placed in the path of a tornado. The pods will be equipped with wind sensors and high-quality digital cameras.
Ideally, the research will capture exactly what is happening when buildings are damaged in a tornado, said Josh Wurman, co-leader of the expedition.
“Beyond, hey, dummy, it's the wind, we don't know a lot of details, even though we know the broad strokes,” said Wurman, director of the Center for Severe Weather Research in Boulder, Colo.
“A lot of people are dying in weakly constructed homes,” he said. “We can't make them infinitely stronger. The question is what reasonable steps can we take to make homes and tornado shelters more reasonably secure. To do that, we need to know more about houses and winds.”
The drive to Randolph, Neb., was the first road trip for the expedition, and the storm they followed spit out only hail and strong winds.
Ultimately, Wurman said: “We watched the sun set.”
Early the following morning, as the storm system barreled through the Omaha area, three campers were injured at Lake Manawa State Park by a falling tree and several patients at the Bellevue Medical Center had to be moved to different rooms because of storm damage to the building.
Despite the absence of twisters to study so far, Wurman remains confident. The expedition extends until nearly the end of June, which includes the busiest time of year for tornadoes in the Central Plains.
Among other things, Wurman said researchers want to find out which is worse:
» A 250 mph wind for one second or 150 mph for one minute?
» A house being hit from one direction, and then three seconds later from another?
» Pure wind striking a home? Or a wind-blown car or telephone pole striking it?
How hard does the wind have to blow to:
» Roll cars, then lift them into the air and turn them into missiles?
» Lift a roof from a house?
Scientists don't even know how strong the winds can get inside a tornado.
Wurman knows they can blow at least 301 mph. That's the official highest wind speed for a tornado, and it's a speed he recorded on a similar field expedition.
“Of course, winds get stronger than that,” Wurman said. “The chance that I recorded the strongest wind in history is pretty unlikely.”
On May 3, 1999, Wurman clocked winds of that speed 100 feet above ground in Bridge Creek, Okla.
At that speed, a tornado is classified as an EF5, which is the highest ranking possible. Tornadoes of that power leave behind emptiness, because the buildings have been obliterated.
This field work has been dubbed ROTATE — for Radar Observations of Tornadoes and Thunderstorms Experiment. It differs from the more highly publicized VORTEX effort in 2009 and 2010, which involved about 100 researchers and sought to understand the cause of tornadoes.
While VORTEX was broader in focus, ROTATE probes, in greater depth, the deadliest minutes of a tornado. Both have been funded, in part, by the National Science Foundation.
This type of field work is necessary because tornadoes are like pinpricks from a cloud. On the grand scale that weather takes place, they are brief slivers of violence and tend to occur in the sparsely populated, largely barren Plains.
And that's the main reason so little is known about them. There's little record of what happens inside of a tornado and only sporadic damage left behind for the forensics work.
“What we really need to push the science forward is to get this integrated picture,” Wurman said.
From VORTEX, researchers learned that secondary downdrafts may be a trigger that causes already rotating masses of air to twist into tornadoes. Like VORTEX, research from this effort probably will take a few years to analyze, Wurman said.
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