The boon and bane of natural water storage in mountains

Mountains are the natural water towers of the world through the capture and storage of atmospheric moisture. Beneficially, in many mountain systems this stored water (e.g., snowpack) is also provided at a time at which precipitation is scarce, yet water demand is high. Yet, the water resource boon that mountains provide can quickly become a bane under extreme conditions that accelerate runoff and lead to the endangerment of the communities that live beneath them. Albeit rare, these extreme rain-on-snow and rain-instead-of-snow events are important drivers of water resource management. In this work, we utilize several observationally based products and climate models to explore mountain snowpack as both a boon and bane to water resource management. These observational products and modeling tools are evaluated using multi-metric evaluation frameworks that isolate their agreements and disagreements in representing the seasonal cycle of snowpack. We then assess if these tools are fit-for-purpose in representing extreme events that lead to both rain-on-snow, and rain-instead-of-snow. We do this using a novel framework that directly connects storm-based event filtering with hydrologic based impact metrics.