Orographic processes in Great Salt Lake-Effect snowstorms

Despite past climatological and modeling studies, accurately predicting Great Salt Lake Effect (GSLE) precipitation remains a formidable challenge to northern Utah forecasters. Moreover, factors controlling GSLE event intensity and morphology, and the influence of surrounding topography are poorly understood. Although past studies have shown that GSLE snow band intensity can be sensitive to the existence of northern Utah mountain ranges, the mechanisms by which these lake-orographic interactions take place are unclear. For this study, multiple events are simulated using the Weather Research and Forecasting model with nested grids to 1.33 km horizontal resolution. This study aims to improve knowledge of the role of topography in GSLE events by performing sensitivity studies involving full and partial removal of northern Utah terrain, for events in various distinct synoptic regimes. Several potential orographic effects are examined, including enhanced over-lake convergence and changes in morphology due to flow channeling or thermally-driven circulations, and enhancement of precipitation structures approaching or intersecting topographic barriers.