Higher Temperatures Lead to More Melt-Freeze Crusts in Snowpacks in Cooler Regions of the Pacific Northwest

This is an accepted article with a DOI pre-assigned that is not yet published.Warming winters will lead to a greater fraction of rain falling in traditionally snowy areas. Here, we investigate the impact of these changes on snowpack stratigraphy, focusing specifically on the presence and duration of melt-freeze crusts. In this work, we use a hydrologic model with high vertical resolution (Structure for Unifying Multiple Modeling Alternatives, SUMMA) to test the sensitivity of melt-freeze crusts to warming. Model runs with up to 100 layers were initialized with observed precipitation and temperature for 2°C and 4°C uniform warming sensitivity tests. We found warming temperatures increased the frequency of crusts at colder sites, while warmer sites had fewer crusts. Melt-freeze crusts increase the complexity of avalanche forecasting and mitigation for highway, recreational forecasting, and ski area operations. These changes to the snowpack will also impact ecosystem function, with greater snow density altering large mammal movements and predator-prey interactions.