Tropical Climate Update

Tropical Low Moving to the Timor Sea

A tropical low ('10U') developed within the monsoon trough in the Arafura Sea to the north of Arnhem Land, and north-east of Darwin, on Monday 23 January. This system is moving west, crossing waters off the Northern Territory coast to the Timor Sea, then to the north of the Kimberley coast.

The system is expected to maintain its west to southwest track before turning south and crossing the Pilbara coast as a tropical low, likely during the weekend. The tropical cyclone forecast models, however, indicate there is a moderate chance the tropical low will develop into tropical cyclone prior to crossing the coast. Whether the system is a tropical low or tropical cyclone, it would potentially lead to widespread rainfall and strong winds affecting the Kimberley and Pilbara regions of Western Australia into the weekend.

Whilst the overall chances of this tropical low developing into a tropical cyclone are moderate at best, and there are no other imminent risks of tropical cyclone development in the near future for northern Australia, it is important to note that the region is in the historically highest risk period of the tropical cyclone season: January, February and March are the peak period for tropical cyclone activity across northern Australia. In addition, the La Niña in the Pacific continues, and the Coral Sea remains very warm (Spring 2022 was warmest on record, and December 2022 was the 2nd warmest) so conditions remain favourable for tropical cyclone formation.

Across northern Australia in the last week there was an easing of monsoon conditions (monsoon break) as the monsoon trough moved north of the Northern Territory and caused heavy rainfall in the Tiwi Islands. The Monsoon trough is currently becoming more active in the central Indian Ocean (outside of the Australian region). Whilst this easing of the monsoon over Australia is likely to persist this week, isolated showers and thunderstorms (some severe) are still likely to be experienced across northern Australia.

For the current tropical cyclone forecast, read at Western Region outlook

Madden–Julian Oscillation Remains Strong in the Central and Eastern Indian Ocean

The Madden–Julian Oscillation (MJO) is strengthening in the eastern Indian Ocean. There is a general agreement amongst climate models that the MJO will remain near stationary for the next few days. The MJO is forecast to move eastward towards the western Maritime Continent before it likely weakens in early February.

A strong MJO pulse in the Indian Ocean generally provides favourable conditions for tropical systems (tropical low or tropical cyclone) development in the basin. 

A strong MJO also likely see enhanced easterly winds in the lower atmosphere levels across the northern Australian regions, thus the monsoon break will persist over the next fortnight. 

Read more about the Madden–Julian Oscillation