Assessing the impact of global warming on windstorms in the northeastern United States using the pseudo-global-warming method
Windstorms resulting from intense synoptic-scale cyclones are an important natural hazard in the current climate of the northeastern United States, but their likely response to global climate non-stationarity is poorly understood. This study investigates the ability of the Weather Research and Forecasting model applied at 3.3 km resolution to simulate historically important cold-season windstorms associated with Alberta Clippers (AC) and Colorado Lows (CL) and then examines how such events may evolve in the future using pseudo-global-warming (PGW) simulations. The simulations encompass approximately 14-day periods that include passage of both a primary-strong extratropical cyclone during which multiple stations exhibited 10-m wind speed observations > 20 ms−1, and a secondary-weak mid-latitude cyclone. The thermodynamics changes projected in the pseudo-global-warming (PGW) experiments lead to a modest decline in maximum wind speeds. The marginal probability of 10-m wind speeds > 14.3 ms−1 drops from 6.6 to 5.3% during the intense AC and from 9 to 6.5% for the intense CL. Similarly, the probability of nonzero precipitation in any grid cell/3-h time interval declines from 2.44% in the control simulation of the intense AC to 1.59% in the PGW simulation, and from 3.39 to 2.67% for the intense CL. Virtually all snow during the CL that occurred during March 2018 is simulated as other hydrometeor types in the PGW experiment, and the spatial extent and location of very heavy precipitation are also greatly modified.