An Extended Hail Climatology for Sydney, Australia, Derived from a Storm Database, Reanalysis, Volumetric Radar and Sounding Data

Severe hailstorms are a frequent occurrence in the eastern New South Wales region of Australia, and are one of the costliest natural disasters experienced in the area. Understanding the spatiotemporal distribution of severe hailstorm development is crucial for identifying the occurrence of hailstorm hotspots, changes in hailstorm distribution and frequency, and for improving forecasting capabilities. While Sydney is the most populated city in Australia, research into hailstorm development over the region and the mechanisms of formation are not extensively studied. Here, an extended and comprehensive climatology of the Sydney metropolitan region is presented, spanning the years 1950 to 2018. An observational database will be utilized to identify hail days and is supported by volumetric radar observations in which daily maximum expected size of hail (MESH) grids are produced. Identification of potential hailstorm days through analysis of environmental parameters including CAPE, wind shear, freezing level and helicity will be computed using dynamically downscaled high-resolution (10 km) regional reanalysis (NSW and ACT Regional Climate Modelling, NARCliM) data and archived upper-air soundings.