Understanding the drivers of climatological hailstorm hotspots in eastern Australia - The Coastal Convective Interaction Experiment (CCIE)

An understanding of the drivers which modulate hailstorm frequency and intensity across many years is often elusive at the local scale (<10km), yet this knowledge is critical for improving the skill for regional severe thunderstorm forecasts and nowcasts. Thunderstorm affected communities and experienced regional forecasters develop an ad hoc awareness of this hailstorm "hotspot" behavior, however, a lack of sufficiently long and robust observational datasets has limited prior research at the required fine spatial scales. The Coastal Convective Interactions Experiment (CCIE) focuses on quantifying hailstorm hotspot activity for the South East Queensland (SEQ) region of Australia and understanding the meteorological conditions which result in this anomalous spatial behavior of thunderstorms. This paper presents a 17 year climatological analysis of SEQ hailstorms from the perspective of operational radar, ERA-Interim and weather station datasets, identifying the sea breeze circulation as a primary driver of the hotspot distribution in SEQ. Furthermore, preliminary results from a two-season field campaign which targeted both the sea breeze circulation and thunderstorms developing in the established climatological hotspot regions is also presented. This observational approach highlights the mechanisms which occur during a sea breeze - thunderstorm interaction and the potential key predictors of convective intensification follow the interaction.