Multiridge Orographic Precipitation in Continental Mountain Environments

University Of Utah, Salt Lake City UT

Investigators

Abstract

Orographic precipitation refers to rain or snow that develops due to the uplift of air moving over elevated terrain. This kind of precipitation is often thought of in locations with sharp, significant elevation differences from near sea level to mountain peaks, like the Sierra Nevada in California or the Cascade Mountains in the Pacific Northwest. However, orographic precipitation can also be created in other locations such as the Great Basin in the Intermountain West. This study will investigate multi-ridge orographic snowfall enhancement in Utah, where air flow is disturbed over multiple parallel mountain ridges. The main impact of the project will be on the downstream potential for improved forecasting of societally-impactful winter weather events. The project also has a significant education and outreach effort, helping to train the next generation of scientists and making science accessible to the general public. This project aims to advance knowledge of the processes that affect the fine-scale distribution and intensity of orographic precipitation in continental multiridge mountain environments, focusing on the eastern Great Basin in Utah. The research team poses two main questions: 1) How do terrain-induced gravity waves influence the intensity and distribution of precipitation generated during flow over broadly separated parallel mountain ridges, and 2) What are the causes and mechanisms of northwesterly flow precipitation extremes over the ridge-canyon orography of the central Wasatch Range? Both questions will be addressed through a combination of observations and numerical modeling simulations. Observational analysis will consist of a radar climatology, use of reanalysis datasets, and new vertical profiling radar, disdrometer, and precipitation observations. The numerical modeling work will use the Weather Research and Forecast (WRF) model in normal and Large-Eddy Simulation (LES) modes, and semi-idealized Cloud-Model 1 (CM1) simulations. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.