Idealized Simulations of the Sensitivity of Supercell Thunderstorm Behavior Near Complex Terrain to Storm Maturity and Approach Angle

Abstract Complex terrain substantially influences weather systems, with prior work documenting impacts to intensity, longevity, and severe weather production of supercell thunderstorms. However, the extent to which these impacts are sensitive to the maturity of the supercell and its angle of approach to the terrain is not well understood. These sensitivities were systematically tested through idealized simulations of supercell thunderstorms traversing the complex terrain of the central and southern Appalachian Mountains. Three maturity levels were imposed by varying the initiation location of the supercell, while the approach angle was varied by rotating the wind profile of the background environment. Supercell evolution was also compared to a simulation with flat terrain. The results demonstrate that supercell intensity, longevity, and motion metrics vary considerably and are sensitive to supercell maturity and approach angle. Supercells initiating closer to the terrain experienced the largest impacts to intensity and longevity, while impacts were more varied among approach angles and highly dependent on localized terrain features traversed. As the approach angle became more perpendicular to the principal crest, low-level rotation was more frequently enhanced due to channeling flow.