• Ex-tropical Cyclone Ellie spent more than two weeks moving over the Northern Territory and Kimberley region of Western Australia.
  • Ellie brought substantial rainfall and flooding to the region, with the Fitzroy River flood level exceeding the previous record by almost two metres.
  • Dimond Gorge and Napier Downs received weekly rainfall totals of 830.2mm and 701.2 mm.

Over the 2022 Christmas and New Year period, ex-Tropical Cyclone Ellie spent over two weeks moving slowly across the Northern Territory and the Kimberley region of Western Australia. Ellie brought heavy rainfall and record-breaking river flooding to multiple locations.

Ellie made landfall near the mouth of the Daly River in the Northern Territory on 22nd December 2022 as a category 1 tropical cyclone. Ellie weakened to a tropical low as it travelled southeast over land, and brought substantial rainfall to many areas including Timber Creek, which saw over 200 mm fall during 23rd December and overnight.

The system continued moving south-east, but on 27th December began to track westwards into Western Australia. Between 30th December and 3rd January Ellie stalled over the Kimberley, bringing several days of heavy rainfall. In Dimond Gorge, north of Fitzroy Crossing, 838.8 mm of rainfall was recorded in the 10 days to 6th January, nearly equivalent to the annual average rainfall (Figure 1). Elsewhere in the Kimberley, multiple sites saw rainfall accumulations over the same period exceeding between 300 mm and 600 mm.

Figure 1: Rainfall totals in the week ending 6 January 2023. Source: Bureau of Meteorology.

These totals resulted in a one-in-100 year flooding of the Fitzroy River, which recorded a peak river level of 15.8 metres on 4th January, beating the previous record by 1.8 metres. Ellie then tracked westwards towards Broome, with more than 400 mm rainfall recorded at Broome airport between 4th and 6th January, flooding the Roebuck Plain and cutting off the town by road. The low then tracked southeast, weakening and eventually dissipating on 8th January.

Over 200 people were evacuated by the military from the Fitzroy Valley, and many settlements including Indigenous communities were left isolated. The Fitzroy River Bridge, a vital piece of infrastructure in the Kimberley, was irreparably damaged. A new bridge is under construction with an estimated cost of $200 million. Because of the damage to critical transport infrastructure, trucks were unable to access the region, causing supermarket food shortages. A $6 million tourism package was announced to alleviate the cost of flights into the region. As of May 2023, the total cost of Cyclone Ellie was estimated at $322 million.

We have not attributed this tropical cyclone to climate change, but that does not mean climate change has not played a role. The science implies climate change could result in fewer occurrences of tropical cyclones in Australia, but the proportion of intense cyclones such as Ellie may increase.

Research contact:
Dr Doug Richardson, doug.richardson@unsw.edu.au