Some weird little Tornado things done for a film. They weren't really interested in the smokey look it turned out. Done after hours. Its kinda meh. lot of artifacts, pops from re-timing. What I took away from here is that FumeFX is not very ideal for making large tornadoes. I honestly think tornado should be faked with volumetric particles, twister style.
Making a magic tornado? Sure! But something that approaches realism? Use Afterburn or Houdini.