10.3 Influence of Boundary Layer Turbulence on Near-Ground Rotation in Quasi-Linear Convective Systems

Wednesday, 26 July 2017: 11:00 AM
Coral Reef Harbor (Crowne Plaza San Diego)
Christopher J. Nowotarski, Texas A&M Univ., College Station, TX

Though most strong to violent tornadoes are associated with supercell thunderstorms, quasi-linear convective systems (QLCSs) pose a risk of tornadoes, often at times and locations where supercell tornadoes are less common. Because QLCS low-level mesocyclones and tornado signatures tend to be less coherent, forecasting such tornadoes remains particularly difficult. The majority of simulations of such storms rely on horizontally homogeneous base states lacking resolved boundary layer turbulence. Previous work has suggested that heterogeneities associated with boundary layer turbulence in the form of horizontal convective rolls can influence the evolution and characteristics of low-level mesocyclones in supercell thunderstorms. This study extends methods for generating boundary layer convection to idealized simulations of QLCSs. QLCS simulations with resolved boundary layer turbulence will be compared against control simulations with laminar boundary layers. Effects of turbulence and resultant heterogeneity in the near-storm environment on bulk storm characteristics and the intensity, morphology, and evolution of low-level rotation will be presented and discussed.
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