Weekly Tropical Climate Note

Heavy rainfall for northern Australia

Parts of northern Australia had their highest on record July monthly rainfall totals during the last week. The highest totals were around the central Queensland coast, where some sites set new July daily and monthly rainfall records.  Some sites near the Queensland coastal town of Yeppoon had more than 400 mm in 72 hours. Parts of the northwestern Northern Territory also received their highest July rainfall totals on record, but the amounts were relatively modest compared with the Queensland totals. The weather feature which produced the rain over coastal Queensland is forecast to move inland and generate further significant falls across central Queensland for the next two or three days.

Historically, heavy rainfall events have been a feature for eastern Australia in the May to August period following the breakdown of strong El Niños (e.g., 1998, 1983, 1973 and 1906), regardless of whether or not it is associated with a transition to La Niña. During this most recent event, the weather system responsible for the rainfall was assisted by the record warm waters which surround Australia's northern coast. These warm waters are a source of extra moisture – which is evaporated into the air and transforms into the clouds which generate the rain.

Indian Monsoon remains active

The northernmost extent of the Indian Monsoon currently lies over northern India. An active monsoon trough over the region has produced heavy rainfall in recent days, with flooding and multiple fatalities reported. While the strength of the monsoon flow over the Indian subcontinent has recently eased, the southwesterly winds associated with the monsoon have persisted over India and much of South-East Asia.

Most climate models indicate that the Madden–Julian Oscillation (MJO) will remain at moderate levels over the Indian Ocean for the next week, so monsoon flow over India is likely to continue and possibly be reinvigorated. Rainfall models suggest that northern India and adjacent regions may see further significant rainfall totals in the coming week.  Typically, when the MJO moves over the Indian Ocean at this time of the year, cloudiness and rainfall is enhanced across an area of the northern hemisphere which extends from the Arabian Sea to South-East Asia. The presence of the MJO is expected to be relatively short-lived, with the majority of models indicating the signal will weaken over the Indian Ocean later this week.

See the Bureau's MJO Monitoring for current MJO information.

Negative Indian Ocean Dipole strengthens

Sea surface temperatures show a negative Indian Ocean Dipole (IOD) in the Indian Ocean. Latest values of the IOD index indicate that the dipole has strengthened in recent weeks. Climate models indicate that the negative IOD will persist through to the end of spring. A negative IOD typically brings warmer daytime and night-time temperatures to northern Australia. Find out more about the Indian Ocean Dipole.

In the tropical Pacific Ocean, although La Niña remains possible, recent model outlooks have eased back their forecasts for La Niña in 2016. Current observations do not show any indication that La Niña is underway, with all indicators within their neutral range. Recent observations, combined with current climate model outlooks, mean the Bureau's ENSO Outlook remains at La Niña WATCH. This indicates the likelihood of La Niña forming in the coming months remains at 50%. If La Niña develops, rainfall in the build-up months and during the northern wet season is typically above average over northern Australia.

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

Product code: IDCKGEW000

Further information

(03) 9669 4057