There are still unanswered questions, such as why some supercell's develop tornados, whilst others do not. Also, the question of the mechanism by which tornados dissipate their energy has not been entirely sorted out. One can say, however, that tornado development requires two conditions: strong thermal convection, and little or no low-level wind shear - such as might occur around large buildings. So the optimum conditions for tornado development are large flat open plains in which warm and cold fronts are converging.