Hail Trajectories in a Wide Spectrum of Supercell-Like Updrafts

Abstract

Modeled hail trajectories have previously been studied in individual observed supercells or in simulated supercells with similar background environments. To explore the impact of changing updraft structure on hail formation from a different perspective, this study analyzes detailed hail trajectories in a large ensemble of time-averaged supercelllike updrafts. The updrafts are created with an idealized heat source, which allows the systematic investigation of the full range of updraft widths and intensities reported in the literature. The simulations exhibit a dominant hail trajectory pathway with a single ascent and a curved horizontal trace. However, a systematic shift in the trajectories and in their start and end locations is found with increasing updraft intensity and updraft width. Furthermore, wider updrafts but with only moderate intensity provide optimal conditions for the hail of most sizes. The exception is giant hail, which requires both wide and intense updrafts. This result is partially linked to the occurrence of an alternative trajectory pathway characterized by the recycling of hailstones (1–4 cm) in the back-sheared anvil region, which then grew to giant size after reentering the updraft.