Supercell thunderstorms in Europe - climatology, morphology and climate change

Supercell thunderstorms are among the most hazardous convective storms in Europe, yet their climatology and environmental conditions are poorly constrained. Using km-scale climate simulations, we present a pan-European supercell climatology for the current climate and assess changes in a +3 °C global warming scenario. Supercells preferentially occur near mountain ranges, with a pronounced maximum over northern Italy and the southern Alps. In the warmer climate, supercell frequency increases by 11% and shifts northeastward and toward higher elevations, while decreases over southwestern Europe are linked to regional drying.

Supercells occur in environments with enhanced instability and deep-layer shear. The storm population splits into 87% right-moving (RM) supercells and 13% left-moving (LM). RMs exhibit more coherent structures and larger high-intensity areas than LMs, while LMs occur in a narrower range of warmer, drier and less stable environments. In the warmer climate, greater instability and increased shear lead to stronger hazards, including hail, lightning and intense precipitation, with hazard and frequency increases being particularly pronounced for LMs.

These results highlight robust changes in European supercell occurrence and associated hazards in a changing climate.