Tornado Tech: How Drones Can Help With Twister Science - NPR

Tornado researchers want to use small drones, like this one called the Noctura, to study the storms.

Andy Arena/Oklahoma State University

Oklahoma was hit particularly hard by two massive outbreaks this year in what's been another deadly season of tornadoes in the U.S. Despite technology and forecasting improvements, scientists still have plenty to learn about how and why tornadoes form.

Currently, one of the best ways for researchers to understand how tornadoes form is to chase them. So off they go with mobile science laboratories, rushing toward storms armed with research equipment and weather-sensing probes.

It's dangerous work. Three chasers died in one of Oklahoma's May tornadoes because the storm unexpectedly changed directions. And there's also a lot left to chance — only 20 percent of supercell thunderstorms produce tornadoes.

"It's a loaded gun," says Jamey Jacob, an aerospace engineering professor at Oklahoma State University, of the big weather systems. "It's ready to go off, but when and where does it fire?"

One of the downsides of the current tornado research method is that it's passive, Jacob says. "You throw [probes] out there, [and] you hope something gets caught up [in the storm] somewhere," he says.

So he and dozens of other scientists and engineers are remaking tornado technology. They're looking to small drone aircraft loaded with sensors that can be launched from the trunk of a car, far from a potential tornado.

"With unmanned aircraft," Jacob says, "you fly it where you want it to go."

If you open up these drones, the contents could have come from a middle school science project. But the Kevlar shell and the tiny sensors are fit for a high-tech military plane.

Brian Argrow directs the research and engineering center for unmanned aerial vehicles at the University of Colorado, Boulder.

"Being able to sample the pressure, temperature, humidity, wind velocity — that you can't do remotely," he says. "Radar can only do so much at this point."

Scientists think these drones can help them increase warning time from the current 14-minute average to as much as an hour. Argrow says the technology exists, and the planes are ready to go, but many of them are stuck in university laboratories, frustrating researchers.

Drones can provide information about temperature, humidity and pressure that current radar systems can't provide. Above, the Talos drone, which has a 15.5-foot wingspan.

Jamey Jacob/Oklahoma State University

"It's often that technology gets ahead of policy, particularly in this country, and this is an instance where that essentially has happened," he says. "Some of the technology — the capability, anyway — has gotten ahead of what the current air traffic system is able to accommodate directly."

The Federal Aviation Administration declined to be interviewed for this story, but Argrow and his team started working with the agency in 2009 to integrate the new storm-chasing technology into the nation's airspace. They were able to fly into a few storms back then. But it's a very slow, bureaucratic process that doesn't mesh well with fast-developing thunderstorms.

Scientists think if new policies are put in place, these aerial chasers could be widely operational in five years, allowing meteorologists to make more accurate tornado warnings.

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Could global warming change tornado season, too?

OKLAHOMA CITY (AP) — With the planet heating up, many scientists seem fairly certain some weather elements like hurricanes and droughts will worsen. But tornadoes have them stumped.

These unpredictable, sometimes deadly storms plague the United States more than any other country. Here in tornado alley, Oklahoma City has been hit with at least 147 tornadoes since 1890.

But as the traditional tornado season nears, scientists have been pondering a simple question: Will there be more or fewer twisters as global warming increases?

There is no easy answer. Lately, tornado activity in America has been Jekyll-and-Hyde weird, and scientists are unsure if climate change has played a role in recent erratic patterns.

In 2011, the United States saw its second-deadliest tornado season in history: Nearly 1,700 tornadoes killed 553 people. The Joplin, Mo., twister was the single deadliest in American history, killing 158 people and causing $2.8 billion in damage.

The following year, 2012, started even earlier and even busier. Through April there were twice as many tornadoes as normal. Then the twisters suddenly disappeared. Tornado activity from May to August of that year was the lowest in 60 years of record-keeping, said Harold Brooks, a top researcher at the National Weather Center in Norman, Okla.

Meanwhile, Canada saw an unusual number of tornadoes in 2012; Saskatchewan had three times the normal number.

That year, the jet stream moved north and "essentially shut down" tornadoes in the American Midwest said Greg Carbin, warning meteorologist at the federal storm center. A tremendous drought meant far fewer storms, which not only shut off the spigot on rain but on storm cells that spawned tornadoes.

For much of America, tornadoes are seasonal. Typically, there are more during spring, and the numbers dwindle in the worst heat of the summer. Last year "essentially was an extended period of summertime conditions over the U.S.," Carbin said. "The real question is: What is spring now? Is it February?"

"Summer may be happening earlier and may be muscling out what we consider a transition between summer and winter," he said.

The last two seasons aren't alone in illustrating extremes in tornado activity.

Tornado record-keepers tally things like the most and least tornadoes in a month. Records for that category have been set 24 times over the past 60 years. Ten of those records have been set in the past decade — six for the fewest tornadoes and four for the most, Brooks said. Also, the three earliest starts of tornado season and the four latest have all occurred since 1997, he said.

What does that mean?

"We've had a dramatic increase in the variability of tornado occurrence," Brooks said.

The jet stream, a major player in tornado formation, has been in a state of flux, varying wildly in recent years, said Pennsylvania State University climate scientist Michael Mann.

"It's hard to predict future tornado seasons when we don't understand current tornado seasons," Brooks said between sessions at the National Tornado Summit here earlier this week. "We're not sure what's going to happen with the tornado numbers."

A new study in the Bulletin of the American Meteorological Society looks at all sorts of extreme weather, how it is changing because of global warming and how things are predicted to change in the future. The study says tornadoes and the severe thunderstorms that spawn them are the hardest to predict.

Public opinion polls show Americans blame global warming for bad tornado outbreaks, but climate scientists say that's not quite right.

One reason scientists can't figure out how global warming might affect tornadoes is that twisters are usually small weather events that aren't easily simulated in large computer models. And records of tornadoes may not have been accurate over the years as twisters twirled unnoticed around unpopulated areas.

So Brooks and others are looking at the ingredients that cause tornadoes. But even that isn't simple. They look at two main factors: moist energy in the atmosphere and wind shear. Wind shear is the difference between wind at high altitudes and wind near the surface. The more moist energy and greater the wind shear, the better the chances for tornadoes.

The atmosphere can hold more moisture as it warms, and it will likely be more unstable so that means more moist energy, several experts said. But wind shear is another matter. Brooks and Stanford University scientist Noah Diffenbaugh think there will be less of that.

That would suggest fewer tornadoes. But if there's more moist energy, that could lead to more tornadoes. One ingredient has to win out, and Brooks says it's hard to tell which one will. Diffenbaugh says recent computer simulations show the moist energy may overcome the reduced shear and produce at least more severe thunderstorms, if not tornadoes.

Given what's happening lately, Brooks believes there will be fewer days of tornadoes but more twisters on the days when they occur.

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Seth Borenstein can be followed at http://twitter.com/borenbears

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Online:

The National Weather Center: http://nwcnorman.org/

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Valleys May Funnel Tornado Winds

Fans of the TV series "Storm Chasers" may be disappointed — not all tornado scientists race after dangerous weather. Some are more like crime scene investigators, only showing up after the damage has been done.

Such forensic experts can learn a lot from studying the aftermath of a fierce tornado, said Christopher Karstens, a meteorologist at Iowa State University in Ames.

Karstens recently traveled to Alabama to survey the toll of a particularly deadly storm, gaining valuable insights into how cyclones behave when they're forced to churn through mountainous territory.

Tornado trail

In April 2011, hundreds of tornadoes ripped through the Southeast U.S., killing more than 300 people. One particularly savage twister, which at one point swelled to about 1.5 miles (2.4 kilometers) wide, careened tore its way 60 miles (97 kilometers) from Tuscaloosa, Ala.60 miles (97 km) northwest to Birmingham, leaving a trail of rubble in its wake. Karstens rushed to the scene not long after. [5 Deadliest Tornado Years in U.S. History]

Like an expert tracker, the young meteorologist followed the footprints of the tornado as it wound through the thick forests near Tuscaloosa. It was tough going. This stretch of Alabama — which sits at the southern edge of the Appalachian Mountains — is marked by steep ridges that rise close to 490 feet (150 meters) high, then plummet into narrow valleys.

But Karstens didn't mind the trek. In fact, he was interested in how tornadoes themselves are able to cross such terrain. Most tornado research, he explained, is done where it's flat — think the plains of Oklahoma or Kansas — but tornadoes don't just touch down on even ground.

"If you talk to people in Alabama, they'll probably tell you that they have tornadoes as frequently as people in Oklahoma," Karstens told OurAmazingPlanet. So far, however, it hasn't been clear how such rugged terrain can affect tornado winds.

Valley vortex

Lucky for Karstens, his cyclone left behind telling clues — namely, snapped twigs and broken branches. The trick was to observe the wreckage, then "try to understand the winds that produced that damage," he said. Karstens discovered during his first visit and several to follow, for instance, that trees lying in low valleys took a much more severe beating than those resting at the tops of ridges. Trees right in the path of the severe winds even had their bark completely stripped off.

Karstens suspects, but can't yet prove, that as a twister drops into a narrow valley, the winds escaping from its vortex may become trapped by the ridges to either side. Then, similar to gusts in a wind tunnel, these rushes of air surge away from the tornado and down the valley — and quickly. That could make such channels a very dangerous place to be during a storm. It's an interesting observation for twister buffs, but it may also help to keep people safe, said Partha Sarkar, a structural engineer at Iowa State and one of Karstens' colleagues. For instance, once scientists know how tornadoes behave in hilly territory, they may be able to warn people living in particularly wind-prone locales, say at the bottoms of valleys.

This story was provided by OurAmazingPlanet, a sister site to LiveScience.

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