Weekly Tropical Climate Note

NT's Top End still waiting for monsoon onset

The North Australian monsoon has not yet arrived at Darwin for the 2018-19 season. A weak trough north of Australia is likely to persist through the coming week. If the trough moves south over northern Australia in the coming days, it will likely bring showers and possibly storms. The trough is not expected to deepen significantly and Australian Monsoon onset at Darwin is unlikely in the coming days. Monsoon onset normally occurs in late December around Darwin. Later than normal onsets are often associated with El Niño in the Pacific Ocean. Tropical Pacific Ocean sea surface temperatures exceeded El Niño levels at the end of 2018, but have since receded.

Madden-Julian Oscillation to redevelop over Maritime Continent later this week

The past week saw the Madden-Julian Oscillation (MJO) weaken over the eastern Pacific Ocean. The MJO is currently indiscernible. This means it is unlikely the MJO will influence tropical rainfall at the beginning of this week. However, climate models indicate the MJO is likely to redevelop over the Maritime Continent later this week. Under these conditions, at this time of year, parts of Australia's tropical north tend to observe above average rainfall, and typically convection is enhanced over South East Asia. It may also provide a favourable environment for monsoon development.

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