High-latitude lake influence on highly concentrated precipitation from cold-season storms in western Canada

Abstract

Cold-season (October–March) storms, particularly severe snowstorms, are responsible for significant economic losses and have crucial impacts on freshwater availability and ecosystems in high-latitude North America. These snowstorms also contribute to destructive floods during rapid snowmelt. Thus, ecosystems and water infrastructure in Canada are highly sensitive to changes in cold-season storms under global warming. This study employs an object-based approach, specifically utilizing a storm-tracking algorithm, to investigate how cold-season storm precipitation in western Canada responds to climate change under a worst-case warming scenario. In the entire study area, peak daily precipitation greater than 50 mm day⁻¹ within storms significantly increases in both warm and cold seasons. The most extreme storms with highly concentrated precipitation (that is, storms with the precipitation intensity 5 times greater at the storm center compared to the area-averaged intensity), are expected to become more frequent in the future, particularly in the coastal regions and inland lake regions. More importantly, by analyzing the top 20 storms with the highest peak daily precipitation, we found that in the future, lakes will contribute more moisture to the atmosphere through increased evaporation, thereby intensifying the moisture supply and enhancing storm precipitation. Additionally, our findings indicate that future cold-season storms with highly concentrated precipitation may not increase evenly across each month. Warmer lakes in autumn, due to their high thermal inertia, will continue to provide significant local moisture to the atmosphere, which is crucial for the formation of highly concentrated precipitation. These findings suggest significant implications for understanding and predicting the impacts of climate change on storm dynamics and precipitation patterns over inland lakes.