Some 1,200 tornadoes pass through the United States each year — more than any other country on Earth. And, within the U.S., Tornado Alley is their main route.
Scientists have now re-created a devastating supercell that swept through the central Great Plains in 2011. Luckily, the new storm touched down only in a simulation.
Led by Leigh Orf, an atmospheric scientist from the University of Wisconsin, Madison, the researchers used a supercomputer to re-create the tornado-producing supercell in an effort understand the structure and mechanisms at work within these huge storms. Most importantly, they wanted to know why certain storms create such intense tornadoes.
During a four-day period in May 2011, a series of storms spawned tornadoes that devastated parts Oklahoma. “El Reno,” the biggest of these cyclones, swept through the landscape for almost two hours, leaving significant destruction in its wake.
With access to reliable environmental data from the storm, Orf and his team set out to re-create El Reno. Like the tornado, the task was huge, requiring a supercomputer to break the atmosphere into almost two 2 billion grid points 75 miles wide, 75 miles long, and nearly 12.5 miles tall. The team was eventually able to re-create the weather conditions present during the storm and identify the atmospheric factors — from wind speed to humidity — leading up to it.
“We are just starting to really dig into the data,” Orf told Digital Trends, “so we lack definitive results at this time.” However, the researchers have found that corkscrew-like features called helical flows seem to accompany tornadoes but never directly interact with them.
“We also found that tornado formation was associated with many smaller ‘mini-tornadoes’ merging along the forward flank downdraft boundary before the main tornado formed,” he said. “We think that these vortices may play a key role in getting the tornado to form.”
