Dynamically Downscaled Projections of Lake-Effect Snow in the Great Lakes Basin

English Abstract:

Projected changes in lake-effect snowfall by the mid- and late 21^st century are explored for the Laurentian Great Lakes Basin. Simulations from two state-of-the-art global climate models within the latest Coupled Model Intercomparison Project Phase Five (CMIP5) are dynamically downscaled according to the representative concentration pathway 8.5 (RCP8.5). The downscaling is performed using the Abdus Salam International Centre for Theoretical Physics (ICTP) Regional Climate Model Version Four (RegCM4) with 25-km grid spacing, interactively coupled to a one-dimensional lake model. Both downscaled models produce atmospheric warming and increased cold-season precipitation. Great Lakes’ ice cover is projected to dramatically decline and, by the end of the century, become confined to the northern shallow lakeshores during mid-late winter. Projected reductions in ice cover and greater dynamically-induced wind fetch lead to enhanced lake evaporation and resulting total lake-effect precipitation, although with increased rainfall at the expense of snowfall. A general reduction in the frequency of heavy lake-effect snowstorms is simulated during the 21^st century, except with increases around Lake Superior by the mid-century when local air temperatures still remain low enough for wintertime precipitation to largely fall in the form of snow.