The Future of Extreme Winter Windstorms in the US Northeast
Winter windstorms are a major hazard in the Northeastern U.S. in the contemporary climate in part due to the high population density and high-value assets. Given projected changes in population, particularly in the megalopolis extending from Washington DC to Boston, and the deicing of the Great Lakes, these windstorms may profoundly change in the future in terms of their spatial extent, frequency, and associated co-occurrence of snow/ice/hail/heavy rain. Accordingly, we are seeking to develop and disseminate information about possible ‘windstorm futures’ using complementary approaches, including transient simulations and thermodynamic global warming (TGW) experiments on historical storylines performed using the Weather Research and Forecasting (WRF) model with and without changing land use. For the storyline approach, we have performed a suite of simulations with different configurations and used the setting associated with the highest historical fidelity to perform TGW experiments of varying complexity. For the transient simulations, we have nested WRF in the MPI Earth System Model. Preliminary results based on the different TGW simulations indicate minimal changes in terms of the maximum intensity of wind speeds in the windstorms but important changes in spatial extent and the phase and intensity of the precipitation. Importantly, the transient simulation suggests a greater frequency of events with tropical origin propagating into this region, potentially indicating a substantial and important shift in the risk profile that may not be fully captured by the TGW experiments. Methods to reconcile and integrate results from transient and TGW experiments are discussed.