Impact of Climate Change on Intense Derecho Events Using the Pseudo-Global Warming Approach

Derechos cause extensive damage, sometimes amounting to billions of dollars, mainly caused by persistent, severe straight-line winds over a large area. Occasionally, the winds from intense derechos far exceed the baseline classification. In this study, we identified several intense derechos, with wind gusts exceeding 100 mph and sustained wind speeds exceeding the severe threshold of 58 mph for at least 20 minutes at a given location. Few studies have examined how a warming climate would affect derechos, and more work is needed to understand the impacts, especially for these particularly intense derechos. It is too computationally expensive to run century-scale global climate model simulations with fine enough resolution to resolve mesoscale features such as derechos. Therefore, we plan to perform ensembles of convection-permitting simulations with the Weather Research and Forecasting (WRF) model using the pseudo-global warming (PGW) approach to gain insight into what impacts the warming climate might have on the characteristics of these events. Four intense derechos have been selected, for which we will run hindcast simulations at a convection-permitting resolution of 3 km. Five future climate experiments are planned using future climate perturbations from global models that participated in the sixth phase of the Coupled Model Intercomparison Project (CMIP6). The intense derechos will be simulated as if they occurred in the mid-century climate under a high greenhouse emission scenario. The future climate experiments will be compared to the hindcasts to determine changes in the simulated intense derechos. Particular attention will be focused on the changes in wind intensity, areal coverage, and duration of severe wind speeds and gusts. These changes will be compared across all four intense derecho events, although we anticipate focusing on one of the four events in our conference presentation.