Projected Changes to Cold-Season Extratropical Cyclones over Northeastern North America in an Ensemble of Regional Climate Model Simulations

Cold-season extratropical cyclones are responsible for numerous meteorological hazards, including heavy rain and snowfall and damaging winds. In particular, these events impact the highly populated regions of the northeastern United States and southeastern Canada each winter, with sometimes substantial socioeconomic consequences. It is therefore crucial to understand how these cyclones and their characteristics may evolve in the future as the climate changes. In this study, cyclones are tracked in an ensemble of simulations of the fifth-generation Canadian Regional Climate Model (CRCM5) produced as part of the North American component of the Coordinated Regional Climate Downscaling Experiment (NA-CORDEX). Simulations cover the North American domain at 0.11° (~12 km) grid spacing, with initial and lateral boundary conditions provided by three Earth system models (CanESM5, MPI-ESM1-2-LR and CNRM-ESM2-1). Simulations follow observed greenhouse gas and aerosol concentrations from 1950-2014 and at least three shared socioeconomic pathways (SSPs 1-2.6, 2-4.5 and 3-7.0) for 2015-2100. In each of these simulations, cyclones are identified and tracked using TempestExtremes (Ullrich & Zarzycki, 2017; Ullrich et al., 2021), which searches for local minima in sea-level pressure surrounded by closed isobars. Using this dataset, we explore future changes in track density, cyclogenesis and cyclolysis regions and cyclone characteristics (e.g., cyclone intensity, precipitation, winds) for cyclones impacting northeastern North America.