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MyCQU - News Article

News Article

Get set for summer cyclones in NSW

Published:04 September 2020

CQUniversity post-graduate researcher Jessie Gray

Tropical cyclones (TCs) are traditionally thought of as a fact of life only for Queenslanders or people living in the Top End of the Northern Territory and Western Australia.

But with summer on the way, the bad news for NSW residents is that they are not out of the firing line – and never have been – with conditions ripe for cyclone activity this summer.

New analysis of meteorological records and climate modes by CQUniversity post-graduate researcher Jessie Gray has revealed that there were 30 TCs which made landfall within the NSW region between 1863 and 2018, with heightened activity during periods of combined La Niña and negative Interdecadal Pacific Oscillation (IPO) climatic conditions.

The findings are presented in a recent paper published in the Journal of Southern Hemisphere Earth Science Systems, by Ms Gray and her co-authors Dr Danielle Verdon-Kidd, of the University of Newcastle, former Bureau of Meteorology scientist Dr Jeff Callaghan, and CQUniversity Head of Environmental Science Dr Nathan Brooks-English.

The team reported that while these events appear to have occurred at irregular times throughout history, there was heightened activity from the 1950s to ‘70s which aligned with a prolonged period of IPO negative conditions and dominant La Niña patterns. 

“The combination of these conditions may again be on the cards this coming summer, based on the Bureau of Meteorology’s current ENSO Watch and IPO tracking data,” Ms Gray said.

The research paper shows that most TC tracks are focused in upper NSW towards the state boundary line between Brisbane and Coffs Harbour. However, TC tracks have reached as far south as Newcastle, Sydney, Canberra, the Tasman Sea and New Zealand.

The duration of these NSW cyclonic weather events has ranged from just a few hours to up to three days. TC Nancy made landfall near Byron Bay in 1990, delivering 530 mm of rain in just 24 hours, winds of up to 130 km/hour and devastation to infrastructure costing the community AU$197 million.

Similarly, in 2013, ex-TC Oswald impacted both Queensland and NSW, resulting in six deaths, the evacuation of more than 2000 people, power outages to more than 283,000 properties and the closure of 200 schools, costing NSW AU$121m.

In addition, the so-called ‘Sydney Cyclone’ of 1950 featured a record low pressure reading of just 988 hPa in Sydney, resulting in widespread flooding and 10 deaths in NSW.

“It is important to accurately know the past frequency of such events before attempting to forecast future changes in the frequency of landfalling TCs in NSW,” the researchers said.

“The ability to achieve this has been limited by historical databases and the need to better understand the inter-annual and inter-decadal oscillation of NSW landfalling TCs.”

Current TC research has also suggested that changing weather patterns may also result in TCs travelling even further south during their decay, as further southward movement of the sub-tropic jet has reduced wind shear in the eastern basin, contributing to an extension of TC lifespans.

“Other research has also indicated that hourly rainfall associated with TCs is projected to increase 27% along eastern Australia by 2100. Importantly, major coastal flooding in south east Queensland through to the coast of New South Wales may be exacerbated by TCs in the future,” the researchers said.

The impact of man-made climate change on TC patterns is also to be fully understood and will be a future focus of Ms Gray’s research.

The full paper can be found at https://www.publish.csiro.au/es/Fulltext/ES19034