Weekly Tropical Climate Note

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Suppressed rainfall phase likely for northern Australia in coming weeks

After a fortnight when major flooding affected much of tropical Queensland, the coming fortnight is likely to see below-average rainfall across northern Australia. The monsoon trough and tropical low, which acted to focus exceptional rainfall totals upon northern Queensland in the last fortnight, have continued to track eastwards during the past week. The monsoon trough now lies well off the Queensland coast, extending from a low over the Coral Sea, then eastwards over the southwest Pacific Ocean. Monsoon break (dry) conditions have recently developed over northern Australia and are expected to persist in the coming weeks as the favourable conditions which contributed to the enhanced rainfall over Queensland moves further away from Australia.

The northern Queensland flood event was exceptional in terms of its duration and the corresponding rainfall totals and widespread flooding. A large proportion of northern Queensland experienced 10 consecutive days of heavy rainfall, with event rainfall totals in excess of 2000 mm (2 metres) at some coastal locations and more than 700 mm at some sites in the northern interior. Multiple sites had their highest 7-day rainfall totals on record in the week to 7 February in a strip extending from near Mount Isa, in the far west of Queensland, to Townsville on the east coast.

Away from the Australian mainland, a short-lived tropical cyclone, Neil, developed to the east of Fiji. This storm, which developed from a tropical low embedded in the eastern portion of the same monsoon trough which affected Queensland, dissipated within 24 hours of being designated a tropical cyclone.

A tropical low near Vanuatu has a moderate to high chance of intensifying to tropical cyclone strength in the next 24 hours. Further information is available at the Vanuatu Meteorology Department.

Madden–Julian Oscillation approaches eastern Pacific Ocean

The pulse of the Madden–Julian Oscillation (MJO) which contributed to the development of the monsoon trough over Queensland is now well away from the Australian region. The MJO's recent location has become difficult to accurately discern due to interaction with a separate, westward-moving tropical wave (an equatorial Rossby wave), but there is high confidence that this pulse of the MJO is no longer enhancing rainfall over northern Australia. At this time of the year, active monsoon conditions over Australia are often associated with an enhanced phase of the MJO, while a monsoon break period is typically correlated with a suppressed phase of the MJO. An MJO pulse over the eastern Pacific typically results in suppressed rainfall for northern Australia and the broader Maritime Continent.

Climate models agree that the MJO is not likely to be in a favourable location for enhanced rainfall across northern Australia for at least the next fortnight. Thus, there is an increased likelihood that the current monsoon break across northern Australia will persist for this period. During a monsoon break, rainfall may still be prevalent across the tropics, but is generally associated with isolated showers and thunderstorms as opposed to widespread rainfall over lengthy periods.

See the Bureau's current MJO monitoring for more information on the MJO.

 

Product code: IDCKGEW000

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