Dynamics of Simulated High-Shear, Low-CAPE Supercells

Abstract High-shear, low-CAPE environments prevalent in the southeastern United States account for a large fraction of tornadoes and pose challenges operational meteorologists. Yet, existing knowledge supercell dynamics, particularly context cloud-resolving modeling, is dominated by moderate- to high-CAPE typical Great Plains. This study applies high-resolution modeling clarify behavior supercells more poorly understood environments, compares them benchmark simulation higher-CAPE environment. Simulated supercells’ main updrafts do not approach theoretical equilibrium level; their largest vertical velocities result from buoyancy, but dynamic accelerations associated with low-level mesocyclones vortices. Surprisingly, tornado-like vortex parcels also sometimes stop ascending near top instead carrying vorticity upward into midlevel updraft, contributing shallowness. Each these behaviors attributed perturbation pressure gradient that are maximized low levels, which predominate when buoyancy small.