Future Changes in U.S. Extratropical Cyclones and their Associated Mean and Extreme Precipitation, Snowfall, and Surface Winds.

During the cool season, severe Extratropical Cyclones (ETCs) and their associated fronts can produce hazardous weather events that include heavy rain, snow, and strong winds. Such events lead to significant losses of human life and property and account for many of the billion dollar weather- and climate-related disasters that plague the U.S. Given the devastating impact ETCs can have, stakeholder communities need robust projections of future changes in ETCs and their associated extremes to help them develop resilient adaptation plans. This study uses a storm-centered approach to examine future changes in mean and extreme ETCs and their associated precipitation, snowfall and surface winds in ERA5, CMIP6 and the CESM2 Large Ensemble. Extratropical cyclones are tracked by the 24-hour difference in mean sea level pressure using TempestExtremes. Storm-centered precipitation, snowfall, and surface winds are then identified within a 15º radius of each storm center. Long-term trends and the interannual variability of the frequency and intensity of the ETCs are examined over the Midwest, Northeast, and Southern portions of the U.S. Regional storm composites are created to examine the ability of the models to capture storm-relative precipitation, snowfall, and surface winds characteristics, through comparisons to ERA5. Finally, future changes in these storm characteristics are also examined.