A numerical simulation of cyclic tornadogenesis

In the last 35 years, the understanding of tornadic storms has increased dramatically as a result of numerical simulations, storm interceptions, radar observations, and theory. Significant progress has been made in the understanding of both midlevel and near-ground mesocyclogenesis, and recent numerical simulations have progressed further downscale to the study of tornadogenesis within a full cloud model. However, the process whereby a single storm produces a periodic succession of mesocyclone and/or tornadoes, i.e. "cyclic mesocyclogenesis/tornadogenesis" has only recently been studied in detail via radar observations and numerical modelling.

In this study, the dynamics of cyclic tornadogenesis will be explored using idealized three-dimensional adaptive grid numerical simulations. Building upon a previous study of cyclic mesocyclogenesis, we will focus upon the mechanisms of initial tornadogenesis, the evolution of the occlusion process, and the processes of mesocyclone/updraft redevelopment and tornadogenesis associated with subsequent cycles. Preliminary results will be compared with recent observations and existing theories of cyclic mesocyclogenesis/tornadogenesis. Some of the difficulties and outstanding questions involved in high-resolution numerical storm modelling will be briefly noted.