158 Sensitivity of Tornado Evolution to Changes in 0-500 m Wind Shear in High-Resolution Simulations

Thursday, 25 October 2018
Stowe & Atrium rooms (Stoweflake Mountain Resort )
Michelle A Elmore, Saint Louis Univ., St Louis, MO; and C. A. Finley, L. Orf, B. D. Lee, and R. B. Wilhelmson

High-resolution numerical simulations of a tornadic supercell are run to test the sensitivity of tornado genesis and evolution to changes in the environmental wind field in the lowest 500 m above the surface. The thermodynamic and kinematic vertical profiles from the 24 May 2011 El Reno tornado environment are used in the base simulation (Orf et al. 2017). The winds were adjusted in the lowest 500 m to alter the direction of the 0-500 m shear vector while maintaining the same 0-1 km storm-relative helicity. Preliminary results of lower-resolution simulations at 100-200 m grid spacing show storm sensitivity to these changes by altering the evolution of the vortex sheet along the forward-flank boundary which, in turn, affects tornado evolution. Preliminary results from the 30-m simulations will be presented, highlighting the difference in evolution along this vortex sheet feeding into the tornado from the forward-flank boundary.

Orf, L., R. Wilhelmson, B. Lee, C. Finley, and A. Houston, 2017: Evolution of a long-track violent tornado within a simulated supercell. Bull. Amer. Meteor. Soc., 98, 45–68, https://doi.org/10.1175/BAMS-D-15-00073.1.

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