Although scientists have made a lot of progress in studying tornados, there is still no definite way of predicting them.
Scientists have learned a lot by studying tornadoes. The knowledge gained has helped significantly in determining weather patterns and various aspects of storms. But there is still a lot that we don't know.
Tornadoes that form from supercells are the most common type. It's generally known how these tornadoes form, but there are still a lot of specifics missing. For example, no one's really sure why some storms form very intense tornadoes while others form weak ones.
There are other kinds of tornadoes whose formations no one is sure about, though. Long-lived tornadoes and tornadoes with multiple vortices are, for the most part, a mystery. There have been attempts to understand them, but none have succeeded.
One of these attempts was with a device nicknamed TOTO, which was the inspiration for the device used in the film 'Twister.' Instead of balls that flew around in the tornado, TOTO was a heavy metal cylinder.
Essentially, for the device to work, scientists had to take a 250-pound device to a field with nothing around, get it off the truck and in the correct position, and then hope that the tornado happened to cross its path. Sounds hard enough, but there's always the increased risk of being struck by lightning while standing in an open field handling a metal object in the middle of an intense storm.
TOTO actually almost worked once, but sadly it was too top heavy and was knocked over by the winds of the weak tornado before it ever got to work.