Weekly Tropical Climate Note

Dry season conditions to return to northern Australia

After a week when out-of-season rainfall was recorded across parts of northern Australia, a return to the usual dry season southeasterly trade winds is expected in the coming week. As a result, parts of Queensland's northeast coast will experience moist onshore winds and regular shower activity, while inland parts of northern Australia will experience low humidity and no rain.

Northwest Australia continues warmer than average. With the relatively mild conditions continuing across southern Australia, the southeasterly trade winds continue to transport warmer than average continental air over much of northern Australia, with the northwest of the continent particularly warm for this time of year. The annual shift to relatively cooler temperatures across northern Australia won't occur until the south of the continent drops in temperature, which usually requires a series of strong cold fronts. This is not expected to happen in the coming week.

Madden–Julian Oscillation moves over western hemisphere

A pulse of the Madden–Julian Oscillation (MJO) currently lies on the other side of the planet, with respect to Australia. Climate models predict it will track east across African longitudes in the coming week. In this scenario, the tropical regions near Australian longitudes, including the Maritime Continent to Australia's north, are likely to see a period of suppressed rainfall in the coming weeks.

At this time of the year, northern Australia is typically not influenced directly by rainfall associated with the MJO. However, last week the MJO was tracking across the Pacific and late-season tropical cyclone activity formed. Hence, the MJO can generate regional conditions which are favourable for tropical trough or tropical low formation to Australia's north, which can significantly affect parts of northern Australia under favourable weather conditions. 

While suppressed rainfall across the tropics in Australia's region is likely in the coming weeks, there is currently some non-MJO wave activity (equatorial Rossby wave and Kelvin wave activity) to Australia's north, which may see periods of above-average rainfall across parts of the Maritime Continent during the next few days.

Read more about the Bureau's current MJO monitoring.

ENSO and IOD update

In recent weeks, most international climate models have indicated a reduced chance of El Niño developing in the coming months. While this is encouraging for the parts of northern Australia which have experienced lower than normal rainfall in recent months, a forecast development of a positive Indian Ocean Dipole (IOD) event means that the rainfall outlook for much of this region remains below average for the next three months.

Read more about the Bureau's current ENSO monitoring.

Product code: IDCKGEW000

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