Simulations of satellite-detected hailstorms to examine damaging hail occurrence in Australia's tropics

Hail is a leading source of insured losses globally, but the occurrence of damaging hail in tropical regions is subject to large uncertainty. In the tropics globally, satellite-based hail detection often detects the presence of ice aloft, and hail proxies frequently show hail-prone conditions driven by high convective instability. However, high melting rates in these warm regions may modulate the amount of hail reaching the surface, and it is therefore often assumed that satellite-based methods overestimate hail occurrence in the tropics. The extent to which damaging (> 2 cm) hail reaches the surface in these warm regions is not well quantified, owing to a sparsity of observational records in many tropical regions. Here, we used high-resolution numerical weather simulations in an ensemble setup with varying microphysics schemes to examine the plausibility of damaging surface hail occurrence, for satellite-detected hailstorms in Australia's tropics. The simulations explicitly estimated hailstone size at the surface using a column model for hail growth and melt. The results show that a significant subset of the cases could plausibly have produced damaging hail at the surface, with cases with simulated surface hail exhibiting greater mid-to-upper level moisture and higher instability than cases without hail. These results may help improve process understanding for hail in the tropics worldwide.