Impact of Climate Change on Extreme Extratropical Cyclones in the Northeastern U.S.

Extratropical Cyclones (ETCs) have the potential to produce high-impact weather in mid-latitudes leading to extreme precipitation, winds, and storm surge events. Despite the societal and economic impacts of ETCs, gaps remain in our understanding of how ETCs and their related hazards will change in a changing climate. In this study, we will evaluate systematic changes in end-of-century ETC characteristics including intensity, translation speed and storm size, with a particular focus on evaluating how wind hazards related to ETCs are expected to change under future climate conditions. We leverage the 100-member CESM2 Large Ensemble (LENS2) dataset to identify ETCs that transect the Northeastern U.S. We find that while the annual number of ETCs is projected to decrease, storms with the highest near-surface wind speeds and lowest pressure anomalies are increasing under warmer conditions. We also observe track density changes in extreme future ETCs in the Northeast, with ETCs more frequently having southeastern trajectories (moving through the Southeastern U.S.) and less zonal movements. Additionally, we leverage the variable resolution capabilities of MPAS to downscale hundreds of intense ETC events from LENS2 to 3-km grid spacing over the Northeast. We will present analyses of climate change impacts on ETC wind extremes and discuss potential future applications such as the analysis of storm surge hazards from ETCs in a changing climate.