Moving, color pictures of two separate tornados tearing across Nebraska is both terrifying and awesome; a sight, until now, unseen by many experienced meteorologists.
"You could chase storms for decades and never see anything like this," said Dr. David Call, an associate professor at Ball State.
Call has chased tornadoes with university students when he's not teaching them meteorology and forecasting.
"Seeing two tornadoes at the same time is something that happens once every five years or so at best," he estimated.
Even then, Call and other meteorologists said twin tornados are typically much smaller than Monday's. They aren't so close, they don't stick to the ground so long and seldom strike simultaneously.
Call explained, "What makes this fascinating to me is that it seems as if there are two separate tornadoes going on at the same time. It is not one tornado that split. It's not one tornado winding down and another one winding up."
On a severity scale of five, known as the Enhanced Fujita (EF) scale, the National Weather Service ranked one of the tornados an EF-4, with winds of up to 200 miles an hour.
Only a small fraction of all tornadoes are captured in photographs or video. Researchers now have the rare opportunity to study a rare phenomenon using both pictures of the twin tornados and scientific data gleaned from radar images.
"To see two apparent tornados with the same parent storm is remarkable. This is the frontier of our knowledge of how storms work, so this will be a great way to learn more about how extreme weather works," remarked Call.
Most tornadoes aren't photographed because they occur in remote places, last just a few minutes or strike in heavy rain or the dark of the night. The last similar twin tornados were photographed nearly 50 years ago in Elkhart, Ind.