There are aspects of the failure modes of fan discs vs. flywheels. Most fan discs fail due to a huge imbalance due to the loss of a blade. I have done many tests like this and will attest that a fan letting go is not a fun thing.
And Saturday evening, a large and extremely dangerous tornado was reported near Glenn Heights, TX, south of Dallas, according to the National Weather Service. According to the Dallas Office of Emergency Management, there was some damage in the Glenn Heights area, but no reports of damage in the city of Dallas.
How many tornadoes per year occur in tornado alley? It is difficult to say, as Tornado Alley does not have definite  boundaries. If we consider the following states to constitute  Tornado Alley: Texas, Oklahoma, Kansas, Nebraâ¦ska, Iowa, and  Missouri; then our total comes to an average of roughly 450  tornadoes per year.