Tornadogenesis mechanism is still unsolved in spite of a great advancement of observation and computer technologies in the last several decades, causing error in forecast and insecurity and disaster on lives and properties. I would like to focus in this talk, on mechanism of tornadogenesis, especially on the un-clarified mechanism of transition of supercell (or non-supercell) to tornado, based on the “Entropic Balance Theory”. It was developed by the unconventional approach in meteorology, but common in theoretical physics, namely variational formalism as a theoretical experiment. The entropic balance theory was found significant agreement with key features of supercell storms and tornadoes obtained from a number of the analyses of variety of observations over decades, and successful numerical simulations such as by Noda and Niino (2002, 2009). It is reported in a chapter of the proceedings of an international symposium published by Springer-Verlag in March 2009. The entropic balance theory explains well the unique mechanisms such as overshooting of hydrometeors against the head-wind westerlies, mesocyclone, hook echo, storm rear- downdraft and existence of steady state solution, like a nonlinear attractor, of tornadic vortex in entropic balance. In a further development of the entropic balance theory, I found a new form of helicity, which explains the results of the successful numerical simulation, more logically than Lilly’s helicity for supercell and tornado development. The Lilly’s model uses stream function (rotational component) only, while the entropic balance theory uses both rotational and irrotational components which play important roles for the transition from supercell (or non-supercell) to tornado. The new form proposes “wrap-around mechanism” for the transition. The mechanism is physically and thermodynamically better than the Leslie’s dynamical pipe effect mechanism which was developed on the Boussinesq approximation. The wrap-around mechanism shows dynamical and thermodynamical process of the transition, because of the development of axial-symmetry along the vertical axis of the small horizontal scales of O(10m) and temporal scales of O(1min) in a storm. The transition is characterized by that from baroclinic to barotropic environment by wrapping around the singularity type of baroclinic core. The entropic balance theory seems to support the Yamagata’s dipole theory and tele-connection theory of global circulation.