Tropical Climate Update

Madden–Julian Oscillation across Africa to western Indian Ocean

A strong pulse of the Madden–Julian Oscillation (MJO) is currently over African longitudes. International climate models forecast the MJO to move across Africa into the western Indian Ocean this coming week. The pulse is expected to weaken but still maintains moderate strength.

At this time of the year, the MJO influence is transitioning to the northern hemisphere, and therefore has less influence on northern Australia. An MJO pulse near Africa and the Indian Ocean typically act to suppress rainfall across that region, as well as the broader Maritime Continent and far western Pacific.

While the MJO has less influence on rainfall, in this phase, it will typically act to strengthen easterly winds and increase temperatures across northern Australia.

Read more about the Madden–Julian Oscillation

Wrap up of the 2020-21 Australian tropical cyclone season

The Australian Region tropical cyclone season for 2020-21 officially concluded on 30 April. There were 8 tropical cyclones in the Australian Region this season. Among them, 3 cyclones reached severe strength (at least category 3 ): Niran reached category 4 in the Coral Sea within the Eastern Region and later strengthened to the strongest system (category 5) to the west of New Caledonia in early March; Marian and Seroja reached category 3 strength in the Western Region.

Two tropical cyclones made landfall: Imogen entered the Gulf Country in Queensland in early January; Seroja crossed the Central West coast in Western Australia in April, an rare occurrence of a severe cyclone crossing the coast so far south and so late in a season.

In addition to 8 tropical cyclones, there were a dozen or so observed tropical lows in the Australia Region in the 2020-21 season. Among them, 3 notable tropical lows brought significant rainfall to northwestern Australia.

The number of tropical cyclone in the 2020-21 season was below the long-term average of 11 in the Australian Region, though the number of recorded tropical lows was above average for the recent two decades (since 2005-06).