The volume of water stored within seasonal snowpacks in the Upper Colorado River Basin is a fundamental constraint on downstream water availability. Climate change is already altering the partitioning of precipitation between rain and snow. Precipitation delivered as rain instead of snow bypasses a natural reservoir that delays its release and transits through fundamentally different pathways, having profound consequences for runoff production and biogeochemical cycling. Coupled land-atmosphere models are important tools that scientists use to examine effects of climate and climate change on precipitation. An important facet of modeling rain-snow partitioning in atmospheric models is how cloud microphysics are parameterized in these models, which simulate mass and the energy balance of hydrometeors based on important assumptions about parameters like their shape, size distribution, growth characteristics, and other properties. Here we report on numerical experiments examining the degree to which alternative cloud microphysical process representations in the Weather Research and Forecasting (WRF) model lead to variability in spatiotemporal predictions of precipitation in the Upper Colorado River Basin. Within the East River Watershed, created corresponding predictions of snow water equivalent and depth by using the WRF-derived forcing scenarios as input to a land model and compared simulated snow conditions with retrievals from the Airborne Snow Observatory (ASO). Generally, more sophisticated microphysics parameterizations produce better predictions of precipitation and snow water storage when compared to available precipitation and ASO data. Differences in simulated precipitation can, in part, be attributed to how vertical hydrometeor structure in the atmosphere are resolved. This study has important implications for hydrologists that use land-atmosphere models and for atmospheric scientists refining cloud microphysics representations in models like WRF. Field campaigns like the Surface-Atmosphere Integrated Laboratory (SAIL) that are collocated with intensive hydrologic and critical zone process study areas like DOE’s Watershed Function Scientific Focus Area hold promise for co-producing scientific insights that are mutually beneficial to both fields.