Storm mergers. Part 1: Preliminary numerical investigations of merger events

A few recent studies have suggested that many tornadogenesis events happen shortly before or after a merger involving a supercell. However, not all mergers yield tornadic supercells. In fact, many mergers have a detrimental effect on the structure and evolution of the resulting storm. The underlying dynamics and physics determining the outcome of a merger are poorly understood. Thus, gaining a better understanding of the meteorology of storm mergers involving supercells may be of immense help to the operational community.

In order to advance our understanding of the processes occurring during mergers, numerical studies are used to elucidate some general principles. The numerical research uses the Bryan Cloud Model (CM1) and ensemble modeling to investigate the dynamics of idealized storm interactions. While many questions can and will be asked regarding the influence of mergers on various storm attributes, including changes in the thermodynamic and microphysical fields, the focus of this work is on the kinematics and dynamics of the evolving mid- and low-level vorticity.