Winter Windstorms in Pseudo-Global Warming Experiments
Windstorms associated with intense synoptic-scale cyclones are an important natural hazard in the northeastern US. Here we provide a preliminary assessment of their response to global warming using a storyline-based pseudo-global warming framework.
The US Northeast is highly populated and prone to large-scale windstorms - that is, extended periods with expansive areas of damaging wind speeds. The top ten most intense windstorms in the Northeast from 1979-2018 caused over 34 billion USD in total damage in 2020 US dollars. Understanding whether and how such events may change in the future is important to building resilience.
We simulate two 14-day periods that contained two of the most powerful winter windstorms from the historical record and two more typical mid-latitude cyclones. Control simulations (CNTRL) are performed using WRF applied at 3.3 km grid spacing. We evaluate the simulation fidelity relative to a range of observations. We re-simulate the periods with the initial and lateral boundary conditions warmed by 4K, specific humidity increased to hold relative humidity constant and with the Great Lakes deiced (PGW). Maximum wind speeds (WS) during intense cyclones are slightly decreased in the PGW simulations. For example, the marginal probability (in space and time) of 10-m WS > 14.3 ms-1 over land drops from 6.6 to 5.3% for an intense Alberta Clipper and from 9 to 6.5% for a Colorado Low. However, there is spatiotemporal variability in the WS response, and localized increases in WS in the PGW simulations are also indicated.