Mauricio Ilha da Oliveira- April 26- Convective Meteorology Seminar

PhD student: Mauricio Ilha de Oliveira

Friday, April 26, NWC 5600, 3:00pm

Evolution of low-level updraft and three-dimensional vorticity during tornadogenesis in an idealized supercell simulation

Abstract: Among all the hazards inflicted by severe convective storms, tornadoes have the potential to cause the most extreme devastation. Despite large advances in our knowledge of the inner workings of tornadic supercell thunderstorms, the processes that lead to tornadogenesis in these storms have not been completely understood yet. A wealth of observational and numerical data has shown that storm-scale processes within a supercell’s cold pool are the main driver for the generation of (baroclinically and/or frictionally) low-level vorticity which can occasionally organize into persistent “vorticity rivers” that can feed into a developing low-level circulation. Nevertheless, several recent numerical simulation studies have highlighted the crucial role of strong, persistent updrafts at low levels in the ability of a supercell to produce tornadoes.

In this presentation, preliminary results from a high-resolution (100-m grid spacing), idealized numerical simulation of a tornadic supercell including surface drag treatment using the Advanced Regional Prediction System (ARPS) will be discussed. The storm produces two tornadoes in a cyclic fashion but emphasis is placed on the second tornadogenesis event. The evolution of low-level kinematics fields in addition to 3D visualizations during tornadogenesis will be discussed. Preliminary results evidence the rapid formation of forward-flank vorticity rivers that feed into the tornado circulation in agreement with previous studies. In addition, complex, 3D vortical structures surrounding the tornado during genesis and intensification will also be highlighted including suggestions for their formation mechanisms.