Impacts of changing winter warm spells on snowpack ablation

Warm days can feel like a nice break to winter temperatures, however, their impact on the snowpack increases as climate warming continues. Intensification of the magnitude, frequency and duration of anomalous maximum temperature in winter have been observed and it will probably exacerbate the lessening of snowpack in a warmer climate. Therefore, we need to investigate the impacts of changing winter warm spells (WWS) on snowpack dynamics as they will likely change snow accumulation and ablation, driven by a decrease in the snowpack cold content and a potential increase in mid-winter snowmelt events, resulting in reduced snow accumulation by the end of the winter.

This study aims to understand the effect of WWS on the snowpack during the accumulation season over regions with a significant snow accumulation in the North American Cordilleras. First, we quantify the contribution of WWS to the snowpack ablation and ablation rates in the current climate for different ‘hydroclimatic’ regions. Second, we investigate the atmospheric controls of WWS on snow ablation to understand its temporal and spatial variability. Finally, we quantify how much snow ablation might change under a warmer climate and how that varies across the domain. These results are expected to shed some light on key processes controlling changes to future snow accumulation necessary for water resources planning in the Western US.