Tropical Climate Update

Thunderstorms continue in northern and western Australia

In the past week, thunderstorm activity has continued, bringing showers and damaging winds across north-west Australia, extending into central and southern Western Australia. 

Storms brought daily rainfall totals of 30 to 100 mm in the Kimberley, Pilbara and areas further south from 20 to 25 November. A number of locations had their highest November daily rainfall on record.

A severe thunderstorm impacted the community of Tom Price in the inland Pilbara on 20 November. The storm caused many trees to be uprooted, along with damage to a number of buildings

The long-range forecast for the fortnight 29 November to 12 December, issued on 24 November, indicates above-average rainfall is likely to very likely (60% to over 80% chance) for the Australian tropics from the Pilbara and Kimberley in Western Australia to the Top End of the Northern Territory and northern and eastern Queensland.

There is an increased chance of unusually high rainfall for the fortnight (rainfall amongst the wettest 20% of fortnights for this time of year), with the highest chances (at least 3 times more likely) in northern Queensland.

Maximum temperatures are likely to be cooler than average for the fortnight 29 November to 12 December. There is an increased chance of unusually cool days for the fortnight (maximum temperatures amongst the lowest 20% of fortnights for this time of year), across most of the north, with the highest chances (at least 3 times more likely) in the Kimberley of Western Australia and the adjacent central western Northern Territory. 

Minimum temperatures are likely to be unusually warm for the fortnight across the northern Australian coasts.

Tropical low 01U formed in the west of Indonesia

Tropical Low 01U formed to the south-west of Sumatra in Indonesia, about 500 km north-west of the Cocos (Keeling) Islands on Saturday 23 November. 01U is forecast to move into the north-western corner of the Australian Area of Responsibility on 26 November and there is a moderate chance of tropical cyclone formation in the coming days as an active MJO moves from the eastern Indian Ocean into the Maritime Continent. Although it is unlikely that the Cocos Islands will be directly impacted by 01U, thunderstorms and heavy showers are expected to continue in the coming days.

Across the equator in the north Indian Ocean basin, a tropical depression BOB 08 developed in the southern Bay of Bengal, to the south-east of Sri Lanka on 25 November. The Indian Meteorology Department forecasts that BOB 08 could develop into a deep depression and move north-westward towards Sri Lanka and the Tamil Nadu coast in the coming days due to favourable environmental conditions.

It has been a very busy few weeks of Typhoon activity in the North Western Pacific basin. Usagi (Ofel) was first identified as a tropical depression simultaneously as Man-yi (Pepito) in the Pacific on 9 November. Usagi (Ofel) strengthened to typhoon strength on 13 November and made landfall on the Philippines east coast three days later, becoming the seventh typhoon crossing the Philippines this season, and causing further damage and casualties.

Madden–Julian Oscillation moves into the eastern Indian Ocean

The Madden–Julian Oscillation (MJO) strengthened in the western Indian Ocean with a moderate to strong MJO pulse propagating to the eastern side of the basin during the past week.

Most climate models indicate the MJO will continue to move eastwards to the Maritime Continent in the coming week before weakening in the eastern Maritime Continent in early December.

When an active MJO moves into the eastern Indian Ocean and Maritime Continent (phases 3, 4 and 5), it typically triggers a westerly wind burst over the tropical Indian Ocean, Maritime Continent, and northern Australian coast. This can also enhance tropical activity and increase the potential for tropical cyclone development and/or monsoon onset in the Australian region and surrounding basins.