Storm-chasing scientists have wrapped up the most dangerous stage of the largest-ever study on why some storms become tornadoes and others don't.
While their mission didn't produce any "Aha!" moments, the storm hunters were able to study more than 20 tornadoes and gather more information on these storms than ever before, said team member Joshua Wurman of the Center for Severe Weather Research in Boulder, Colo. The findings are leading to a greater understanding of tornadoes, and scientists expect they will ultimately improve tornado warnings and short-term severe weather forecasts [See the storm chasers at work].
Wurman, who has been collecting data on tornadoes for over a decade and has been featured in the television series "Storm Chasers," called the project a "tremendous success" and said he has "high confidence that we will get good results" from combing though the data. This analysis will take several years to complete, he said.
Their $11.9 million project is called VORTEX2.
The first VORTEX project (for "Verification of the Origins of Rotation in Tornadoes Experiment") was conducted in 1994 and 1995. It gathered critical data on supercells, the severe and long-lived thunderstorms that give birth to the most destructive and deadly tornadoes. VORTEX findings were credited with improving National Weather Service tornado warnings.
In VORTEX2, scientists studied the swirling storms across the Great Plains with a flotilla of instruments. The mission ran from May 1 to June 15, the most active part of the tornado season in the Great Plains. Here, violent twisters are more common than any other place in the world and residents are constantly on the lookout for ominous clouds.
"We're studying something that's not just an academic curiosity. It will help people that live in fear of tornadoes," Wurman said.
One of the project's goals is to learn why storms give birth to some tornadoes that can knock only a few shingles off a roof and others that will blow off the entire roof. By learning the differences, scientists hope to give residents a heads-up when a deadly tornado is likely to form in their county — crucial information that often comes too late.
"Eventually we'd like to be able to give tornado warnings that are similar to hurricanes warnings with intensity, timing and where it's going to go. Residents know the category of a hurricane before it hits," Wurman told OurAmazingPlanet.
The average tornado warning is sounded 13 minutes before touchdown. Because the warnings don't provide much time, residents in the path of a tornado are advised against evacuating and urged to seek low-lying ground. If warning times could be improved to 40 minutes, Wurman said, residents could make better choices about the risk.
"If we could make the warnings more precise, maybe evacuations would be a smart thing to do," Wurman said.
Researchers took a step toward learning about violent twisters last spring, during the first phase of VORTEX2. They made key observations of a southeast Wyoming tornado that was rated EF2 on the Enhanced Fujita tornado damage scale, which goes from 0 (minor damage) to 5 (a storm that will completely destroy a house).
The tornado trackers captured numerous other tornadoes and supercell thunderstorms in Colorado and other states across the Plains. They didn't find any massive storms but said the number of storms observed made up for that. The researchers also gathered data on more than 30 non-tornadic storms for comparison.
More than 100 scientists from a number of organizations, including the National Center for Atmospheric Research in Boulder, Colo., deployed an unprecedented fleet of mobile radars and other cutting-edge tools to chase down tornadoes across an area spanning more than 900 miles (1,448 km) from West Texas to southwestern Minnesota.
From the early-morning forecast to the deployment of the instruments, "the whole day is tense," Wurman said.
On each day of operations, VORTEX2 teams positioned equipment about an hour ahead of a potentially tornadic storm. If a storm transformed into a tornado, then things got dicey.
Six vehicles had 45 seconds to drive into the storm, drop data-gathering "tornado pods" and get out of the tornado's path. The timing was critical, and panic was the enemy. Drop the pods too soon and the storm might die out before reaching the instruments. Drop them too late and face 100 mph (160 kph) winds and softball-size hail that can smash windshields.
The work was dangerous, but Wurman touted the project's perfect safety record. If conditions became too severe, the team would call off a chase. On one of the project's last days, a storm in Texas unleashed heavy rains, dangerous floods, high winds and dust clouds, prompting the team to pull back.
With no home base, however, the scientists retreated to their makeshift headquarters — roadside inns. The team remained on the road during the entire six-week study.
"We're sleeping in motels on the highway, eating fast-food dinners," Wurman said. "We're living completely nomadically. We don't know until 6 p.m. where we're going to stay the night — all for the intermittent and rare moments of satisfaction."
Supercell storms can spawn tornadoes within minutes. But this happens in only a small fraction of supercell storms, and standard observing networks and radars often fail to capture the atmospheric conditions that lead to a tornado.
The radar fleet included 10 mobile radars that tracked winds and precipitation. The instruments had a resolution as fine as 100 feet (30 m) and time steps as short as 10 seconds. More than 36 portable surface weather stations blanketed areas in and near target storms. A robotic 12-foot (4-m) propeller aircraft probed the edges of severe storms.
The scientists hope these instruments gathered the key information needed to unravel how tornadoes form. For the VORTEX2 storm chasers, solving this mystery is what the chase is all about.
"When I see something for the first time, that moment of discovery is really a thrill for me," Wurman told OurAmazingPlanet. "I don't get adrenaline from chasing the storms but from seeing something that's never been seen before."