Influences on the formation of a modeled tornado-like vortex

The Regional Atmospheric Modeling System (RAMS) is used to examine the formation of a tornado-like vortex within the simulation of an idealized supercell in a horizontally-homogeneous environment. The vortex achieves a pressure drop of 20 mb, is 1.5 km in diameter, and is associated with 50 m s^-1 winds several hundred meters above the surface. It does not appear that the vortex forms by a 'dynamic-pipe' effect; rather, the vortex rapidly intensifies throughout its depth. However, dynamically-induced pressure perturbations associated with the modeled supercell do seem to be important for concentrating vorticity at the location of the future tornado-like vortex. The effect of microphysics on the evolution of the vortex is also investigated. For example, when the mean diameter of the hail species is reduced, hydrometeors are advected further away from the concentration point of vorticity. This reduces the eventual intensity of the tornado-like vortex because the downdraft associated with these hydrometeors is important to the concentration of vorticity. The significance of these model results to the behavior of real tornadic supercells is discussed.