Determining future thunderstorm-prone environments in Southern Ontario by using statistical downscaling to project changes in convective available potential energy (CAPE)

Abstract

Considering the potential risks associated with thunderstorms, to date, there has been limited analysis on the projection of thunderstorm occurrence trends in Canada. The small spatial and temporal scales of thunderstorms are not resolved in global climate models (GCMs). In this study, the relationship is established between thunderstorm observations from nine weather stations across Southern Ontario, Canada, and daily maximum convective available potential energy (CAPE). The results from the correlation analysis between CAPE and thunderstorm days suggested that the probability of observing a thunderstorm increases as maximum daily CAPE increases. We then utilize the novel approach of applying statistical downscaling (SDSM) to CAPE. After regenerating CAPE over a 30-year reference period (1981–2010) at each weather station, it was determined that the SDSM-modeled CAPE values well compared to observed CAPE values. Future CAPE values up to the end of the current century are then projected using the SDSM models for each station in combination with three GCMs for future climate. The forecast from the downscaling suggested large increases, as much as tripling, in annual mean CAPE, summer mean CAPE, and number of days exceeding a 50% probability and 80% probability of observing a thunderstorm at all weather stations under SRES business-as-usual and RCP 8.5 scenarios for the study period of 2011–2100. All else being equal, this suggests an increase in the number of days with conditions favorable for thunderstorms under a warmer climate.