a tornado is a phenomenon that usually spawns from a supercell thunderstorm,but if it is not a supercell,then it may be spawning from a funnel cloud in which funnel clouds might,and I mean might,produce a tornado. At first tornado expert,Theodore Fujita invented the Fujita scale to measure from F0,F1,F2,F3,F4 and F5,tornadoes. Did you know that Theodore Fujita actually added one more on the Fujita scale,An F6 is a inconsiderable tornado, the wind speed is from 318 MPH,to 500 MPH,and nobody has survived a F6 tornado.