Impacts of Cell Interaction on Storm Intensification: A Dynamical and Microphysical Perspective

In a two-part study, Lee et al. (2006) examined the relationship between cell interaction, supercell behavior, and tornadogenesis during the April 19th, 1996, Illinois tornado outbreak. Part I focused on cell evolution and supercell isolation, and results suggested supercell isolation occurs by two processes: cell merger, and cell attrition along a common boundary. Part II examined the correlation between cell merger and tornado incidence. Results showed 54% of tornadoes formed 15 minutes before or after a storm merger. Jewett et al. (2008) used WRF2.2.1 to study idealized cell interaction simulations by varying the configurations of two initial thermals. They found when one of the initial thermals was positioned to the southwest relative to the other, the presence of the second cell resulted in stronger winds and rotation at the surface over a larger area, though the intensity and longevity of the rotation was highly sensitive to the relative locations. Building from these previous studies, the current research will isolate the dynamical and microphysical alterations from the interaction between two cells that are responsible for subsequent mesocyclone intensification and possible tornadogenesis.