Tropical Climate Update
Northern Australia entering period of increased tropical activity
Monsoonal conditions which have recently been evident across the south-eastern Indian Ocean are expected to become established across northern Australia in the coming fortnight. In recent days a monsoon trough has also started to develop over the northern Coral Sea. Both these monsoonal areas have seen enhanced tropical weather and now have tropical lows and/or tropical cyclones embedded within the associated monsoon troughs.
Typically, the region within and near a monsoon trough provides favourable conditions for widespread and persistent thunderstorm activity, leading to tropical low or tropical cyclone formation under certain environmental conditions. More generally, even when tropical lows/cyclones are not present, an area experiencing monsoonal conditions will normally see higher than average rainfall activity.
The current climate conditions influencing the Australian tropics indicate above-average tropical weather and rainfall is favoured to be a feature across much of the region for the coming fortnight.
Tropical cyclone activity in the Australian region
Two tropical lows recently developed to the northwest of Australia, with one of them recently being assessed as reaching tropical cyclone intensity. Tropical cyclone Freddy developed Monday, 6 February, well off the northern Western Australia coast and is not expected to directly impact the Australian mainland. A second low in the southern Indian Ocean lies well west of the Australian mainland and is expected to become a tropical cyclone south-west of Cocos (Keeling) Island in the next day or two. A third tropical low lies in the northern Coral Sea, well east of the Queensland coast. This tropical low is expected to strengthen into a tropical cyclone in the next day or two and is expected to track roughly parallel to the Queensland coastline thereafter. There are currently no indications that this system will directly impact the Australian mainland; however, this system may pass close to Norfolk Island later in the week.
With active monsoonal conditions expected to be a feature across northern Australia, there is an above-average risk of further tropical low/cyclone activity developing in the coming fortnight. February to March is generally the time of highest tropical cyclone frequency in the Australian region.
Madden–Julian Oscillation to influence northern Australia
The recent, and expected continuing, increase in tropical weather across the Australian region is associated with both an active phase of the Madden–Julian Oscillation (MJO), and regional equatorial Rossby wave activity. A pulse of the MJO which had been located in the tropical eastern Indian Ocean during the past fortnight, recently moved into the Maritime Continent, to the north of Australia, and climate models indicate the MJO pulse is expected to move across the Maritime Continent, before moving into the Western Pacific region the following week. When an MJO pulse is in either of these regions at this time of the year, monsoonal conditions and above-average rainfall are typically observed across northern Australia and the broader Maritime Continent region.
The broadscale monsoonal westerly wind flow which can extend from the south-east Indian Ocean, across northern Australia, and over the south-west Pacific Ocean in such scenarios, is the primary driver of monsoonal conditions. These winds can also weaken the normal trade wind regime across the tropical Pacific Ocean, thus temporarily weakening the strength of La Niña. As the current La Niña event has been in a gradual weakening phase of late, such an episode of the MJO may act to hasten the 2022-23 La Niña's ultimate demise.
Read more about the Madden–Julian Oscillation
Product code: IDCKGEW000
About the Tropical Climate Update
The Tropical Climate Update is published weekly during the northern wet season (October to April). For the remainder of the year it is published fortnightly, on alternate weeks to the Climate Driver Update.
The Climate Driver Update provides a summary of the major climate drivers affecting Australia, including tropical climate drivers.