39HYDRO Analysis of Cold Season Precipitation Dynamics in Complex Terrain over the Upper Colorado River Basin

Cold-season precipitation predictability within the complex terrain of the upper Colorado River basin is vital for water resource management across many western states, as the Colorado River serves as a primary source of water for over 40 million people in the western United States and Mexico. Importantly, this includes supplying water to support crop irrigation for agriculture in these regions. However, precipitation processes in the headwaters of the Colorado River are not fully understood, due in part to the limited amount of observations that scientists have to better understand the processes driving precipitation development and lifecycle. Data gathered in the East River Watershed of Western Colorado during the Study of Precipitation, the Lower Atmosphere, and the Surface for Hydrometeorology (SPLASH) and its sister campaign, the Surface Atmosphere Integrated Field Laboratory (SAIL) provide critical insights to fill these observational gaps. SPLASH and SAIL together deployed numerous radars and other remote sensors over two annual cycles, capturing detailed information on clouds and precipitation in this Colorado River headwaters region.

In this work, we conduct analysis of winter precipitation events to better understand the atmospheric conditions and cloud macro- and microphysical processes that lead to heavy snowfall in the East River Watershed. To do so, we combine near-surface meteorological data across several SAIL and SPLASH sites, large-scale synoptic forcings from reanalyses and other model-supported tools, and radar products to investigate the observed cold-season precipitation dynamics. Specifically, we evaluate key microphysical processes such as secondary ice production and cloud-top generating cells over a subset of cases using these tools to help offer increased insights into winter precipitation mechanisms over this region of complex terrain.