European supercell thunderstorms-A prevalent current threat and an increasing future hazard.

Supercell thunderstorms are the most hazardous thunderstorm category and particularly impactful to society. Their monitoring is challenging and often confined to the radar networks of single countries. By exploiting kilometer-scale climate simulations, we have derived a previously unknown characterization of supercell occurrence in Europe for the current and a warmer climate. The current climate shows several hundred supercells per convective season. Occurrence peaks are colocated with complex topography, e.g., the Alps. The absolute frequency maximum lies along the southern Alps and minima over the oceans and flat areas. Comparing a current-climate simulation with a pseudo-global warming +3°C global warming scenario, the future climate simulation shows an average increase of supercell occurrence by 11%. However, there is a spatial dipole of change with strong increases in supercell frequencies in central and eastern Europe and a decrease in frequency over the Iberian Peninsula and southwestern France.