The initial phase of the Verification of Rotation in Tornadoes Experiment 2 " also called Vortex2 " started May 10 and ran through June 13. A second phase will run from May 1 through June 15 next year.

About 120 people from 18 universities and government agencies traveled more than 11,000 miles during Vortex2's first phase, but found only a strong EF-3 tornado in far southeastern Wyoming that lasted about 30 minutes.

"It was the least number (of tornadoes) in that time period since the early 1990s, and only twice since World War II," said Don Burgess, a research scientist at the University of Oklahoma. "Mother Nature likes to play tricks on us. ... That's why we planned for Vortex2 to be a two-spring experiment, because any one spring can be a bad year."

Burgess said that despite the lack of tornadoes, the first year of the Vortex2 project still proved beneficial, in part because researchers found and recorded information from three tornadic storms that did not produce any twisters.

The experiment is based out of the National Weather Center in Norman. The researchers used 40 vehicles, 11 mobile radars and 80 other separately placed instruments. The original Vortex project in 1994 and 1995 had just one radar.

"We had so much more of everything, we had to figure out how to make it all work together," Burgess said.

Before the experiment resumes next spring, Burgess said researchers will break down and analyze the information gathered from this year's travels.

"The data we collect will feed back into warning decision-making systems and hopefully help us make better warnings," said Robin Tanamachi, a graduate research assistant at the OU School of Meteorology, who participated in the experiment.

Contributing: Information from: The Oklahoman, http://www.newsok.com