The role of environmental and computational parameters in the development and impact of the forward-flank gust front in supercell thunderstorms

Modeling studies of supercell storms have generally shown that forward flank outflow is delineated by a sharp wind shift and that baroclinic generation of horizontal vorticity along this boundary plays a role in the development of low-level mesocyclonic vorticity. However, a few recent observational studies have documented forward-flank gust fronts which are either extremely weak or at times non-existent. In light of these findings, it is important to reassess the conditions that force (or fail to produce) these features within the forward flank of a supercell. In addition, recent studies have shown that the spatial resolution chosen for a model simulation greatly affects the meteorological outcome. Specifically, it has been found that a model using a relatively large grid spacing may not capture the correct evolution of a convective system. However, high-resolution mesoscale models, such as the Advanced Regional Prediction System (ARPS), now allow simulations of supercell thunderstorms with a spatial resolution of <100 m. Comparison of high-resolution simulations to results of past modeling studies would serve to solidify our understanding of the role that the forward flank gust front plays in supercell dynamics. Using the Weather Research and Forecasting (WRF) model, high-resolution sensitivity studies will be conducted to assess the impact of changes in environmental thermodynamic and kinematic parameters on the development, evolution, and impact of the forward-flank downdraft and associated gust front. A statistical analysis of these simulations will be conducted using stepwise linear regression to identify which factors impart the strongest or weakest effects.