Weekly Tropical Climate Note

Madden–Julian Oscillation has weakened

In the Indian Ocean, cloudiness and rainfall was enhanced along the equator this past week, as a strong Madden–Julian Oscillation (MJO) moved eastwards over the region before weakening prior to reaching Maritime Continent longitudes.

Most climate models monitored by the Bureau of Meteorology predict the MJO will weaken further and become indiscernible in the next fortnight. While some models suggest the MJO may briefly and marginally strengthen in about a week’s time, no models indicate the signal will strengthen significantly in the coming fortnight and none predict the MJO will enhance cloudiness and rainfall across the Maritime Continent or northern Australia during that period.

Tropical wave activity is not expected to significantly impact rainfall patterns over the Maritime Continent in the coming week. The dominant driver of tropical weather in the Maritime Continent region is expected to be associated with a burst of westerly winds, which most models forecast for the coming week. This westerly wind burst is a typical feature at this time of the year (see wind analysis chart here) and has the potential to significantly enhance rainfall in parts of the Maritime Continent and South-East Asia.

See the Bureau's current MJO Monitoring information.

ENSO-neutral state continues in the Pacific Ocean

The El Niño–Southern Oscillation (ENSO) remains neutral but continues to show some La Niña-like attributes. In the central Pacific Ocean, sea surface temperatures are slightly cooler than the long-term average, however they remain within neutral bounds and are forecast by most international climate models to remain so for the next few months. The atmosphere above the tropical Pacific Ocean, as indicated by the Southern Oscillation Index and the trade wind regime, also reflects an ENSO-neutral state.

There are some features across the Pacific basin that are suggestive of a La Niña-like pattern, such as warm waters around northern Australia’s coastline and the below-average convection and rainfall near the Date Line, but without coupling between the ocean and the atmosphere, a well-developed La Niña will not become established in the Pacific.

The Indian Ocean Dipole has returned to neutral levels after being in a negative phase since May. 

See the Bureau’s ENSO Wrap-Up for official El Niño, La Niña and IOD information.

Product code: IDCKGEW000

Further information

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