What do large hail, tornado and severe thunderstorm wind environments have in common across continents?

Parameter studies for convective storm environments have historically focused on single continents. Here, we considered severe weather reports (hail, tornadoes, severe convective winds), lightning detection data and ERA5 reanalysis across four parts of the world: Europe, Australia, South America, and the United States. We analyzed convective parameters and vertical profiles of atmospheric quantities for severe and non-severe thunderstorms to better understand which environmental features share similarities among continents and reliably represent convective hazards. Thermodynamic parameters are the most useful proxies of hail and warm season severe winds, whereas kinematic parameters are the most robust predictors of storm severity, especially tornadoes, whose environments feature large contribution of low-level streamwise vorticity. Hail experiences weak near ground winds and the strongest bulk wind shear between 1–3 km while tornadoes and severe winds have the largest shear near ground. Larger hail and stronger tornadoes can be expected with increasing storm-relative winds, moisture fluxes, and mid-tropospheric ventilation (i.e. wind component perpendicular to inflow axis). Extending hodograph to its origin while calculating storm-relative helicity and streamwise vorticity improves tornado prediction, especially for shallow layers (0–100 m). Lifted parcel buoyancy in the hail growth layer (-10°C to -40°C) is important for assessing likelihood of hail. Using peak parcel buoyancy (instead of integrated) leads to more skilful predictions of hail and tornadoes, especially when entraining parcel calculation procedure is incorporated . We also note that some parameters are geographically dependent (e.g. lapse rates), and that parameters, which are good predictors for the occurrence of convective hazards, are typically not the best parameters of their intensity.