The introduction of significantly nonaxisymmetric near surface flow, for example due to large translation velocities of the tornado, strongly affects the corner flow structure.
Time varying near surface conditions lead to a progression of different corner flow dynamics.
For example a high swirl vortex with multiple secondary vortices can evolve into a narrow, intense, low swirl vortex before separating from the surface and dramatically weakening, as the volume of low swirl fluid near the surface is increased with time. When the volume of flow is being increased by translation of the tornado, an individual secondary vortex evolves into a highly asymmetric primary vortex as the translation becomes sufficiently strong with respect to its swirl. We intend to show to what extent rapidly evolving vortices can lead to differing intensities from that obtained from a series of quasi-steady states, and use our simulation results to speculate on whether the asymmetry introduced by the translation, and possibly the rear flank downdraft gust front, into the near surface inflow layer play a role in determining when an existing supercell low level mesocyclone produces a tornado.