3.3 Non-tornadic and tornadic VORTEX2 supercell simulations

Monday, 3 August 2015: 2:00 PM
Republic Ballroom AB (Sheraton Boston )
Brice E. Coffer, North Carolina State University, Raleigh, NC; and M. D. Parker
Manuscript (2.2 MB)

Composite environments of non-tornadic and tornadic supercells sampled during the Verification of the Origins of Rotation in Tornadoes Experiment 2 (VORTEX2) revealed several recurring differences that may potentially be relevant to tornadogenesis. From these VORTEX2 composite environments, we have simulated non-tornadic and tornadic supercells initialized using Bryan Cloud Model 1, including high-resolution horizontal and vertical grids (dx = 125 m, 115 vertical levels), a bottom boundary condition with friction, and advanced microphysics (NSSL double-moment). The simulated supercell in the VORTEX2 tornado environment produces intense, long-lived surface vortices that extend upward to great heights within the simulated storm; the non-tornadic VORTEX2 environment does not. With these simulations, we have started to address the following questions: What are the relative roles of friction and baroclinicity in tornado formation, maintenance, and demise? What is the failure point in tornadogenesis in non-tornadic supercells? Time series and composites, vortex lines, and parcel trajectories will be employed to highlight interesting differences between the non-tornadic and tornadic supercells and to begin examining these unresolved questions.
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