Advances in research on Supercell storms

Purpose Supercells are the most severe and long-lasting type of highly organized convective storms, representing the best organized type with the highest potential for causing disasters and a higher likelihood of producing extreme weather events. This article provides an overall portrait and recent highlights of supercells research, including the unique structure, environmental characteristics, and the formation and maintenance mechanisms of the mesocyclone. Results Conclusion Buoyancy instability is a necessary ingredient of supercells environment, while the dynamic factors such as vertical wind shear and low-level storm-relative helicity are more sensitive parameters for distinguishing supercells from non-supercells. The near-storm environmental profiles based on multi-source observation data are expected to further improve high resolution and highly skilled nowcasting of supercell storms. Supercells of different types and those causing different hazard weather exhibit distinct characteristics in reflectivity factor morphology, dynamic, and cloud microphysical structures. For instance, tornadic supercells have a strong low-level mesocyclone, severe hail supercells have a strong and deep mesocyclone, high wind mesocylones are accompanied by significant mid-level radial convergence, and supercells causing heavy precipitation often have a lower-level mesocyclone. The vertical vorticity of mesocyclone comes from tilting of environmental horizontal vorticity by intense updrafts related to storm. The horizontal vorticity of the mid-level mesocyclone originates from vertical wind shear (wind direction and speed vary with height), while the horizontal vorticity of the low-level mesocyclone has two different origins: one is the low-level environmental vertical wind shear,the other is horizontal vorticity producd by baroclinic near the gust fronts. It’s currently unclear which mechanism is more reasonable or dominant. Moreover, the maintenance and enhancement mechanisms of the mesocyclone are complex and diverse in situations where the mesocyclone being surrounded by heavy precipitation, storm mergers, and the interaction between supercell and mesoscale boundaries in Planet Boundary Layer (fronts, dry lines, gust fronts, etc., and their associated convergence lines). In recent years, based on superhigh-resolution numerical experiment results, the physical conceptual models of the supercell tornadogenes is have been updated. New microphysical characteristics and some dynamic characteristics have been revealed by the dual-polarization Doppler weather radar, enabling more accurate detection of hail sizes. However, the refined physical conceptual model of the growth of large hailstones remains to be improved, and the understanding on the formation mechanism of extreme wind and flash flood related to supercells is still limited.