Damage Associated with Australian East Coast Tropical Cyclones under Climate Change and Preindustrial Conditions

In March 2017 a tropical depression formed off the coast of Queensland, Australia. As the system developed into a tropical cyclone, Debbie was forecast to be the most intense system to make landfall on a populated part of the Queensland coast since Yasi in 2011. Although Debbie officially remained below a category 5, she blew away a number of previous records. The official Hamilton Island weather station wind gusts of 263 km/h exceeded their previous record by 50 km/h. After landfall, Debbie rapidly weakened to a tropical depression, but still managed to become the deadliest and most destructive cyclone to hit Australia since cyclone Tracey in 1974. The reason for this was primarily due to extreme rainfall and flooding. The town of Springbrook measured a record 900mm of rain in 48 hours, nearly equivalent to Brisbane’s annual precipitation and 50% more than Melbourne’s annual rainfall of 600 mm. Importantly, Springbrook is located significantly south of the landfall location and was well out of the predicted area of floods and damage from its initial impact. This behavior is thought to have been exacerbated by the warmer than average SST that was recorded over the Coral Sea along Debbie’s path.

In previous studies the authors used the Hybrid WRF Cyclone Model (HWCM) to show that idealized cyclones making landfall on the Australian East Coast under climate change conditions (Bruyère et al., 2017) consistently result in some of the highest flood producing precipitation well south of the landfall location. In this paper we will describe and discuss implications for the impacts of Debbie-like tropical cyclones under Climate Change and Preindustrial conditions and compare these to observations.

Bruyère, C.L., and Coauthors, 2017: Developing Sustainable Tools for Reducing Weather and Climate Impacts. AMOS, Canberra, Australia, February 2017.