Negative Indian Ocean Dipole emerges as Pacific Ocean remains neutral

05/07/2016

A negative Indian Ocean Dipole (IOD) pattern has established in the Indian Ocean.

Current weekly IOD index values are the lowest in at least the past 15 years. Climate models predict the negative IOD pattern will persist and develop through the southern winter and spring.

A negative IOD typically brings above-average rainfall to southern Australia during winter-spring, with cooler-than-average daytime temperatures across southern Australia, and warmer day and night-time temperatures in northern Australia. Find out more about the Indian Ocean Dipole.

In the tropical Pacific Ocean, sea surface temperatures have continued to cool in recent weeks. With all ocean and atmospheric indicators near normal, the tropical Pacific Ocean is in a neutral El Niño–Southern Oscillation (ENSO) state.

However, a large volume of cooler than normal water below the ocean surface suggests La Niña remains possible in 2016. Recent observations, combined with current climate model outlooks, have left the Bureau's ENSO Outlook unchanged at La Niña WATCH. This means the likelihood of La Niña forming later in 2016 is around 50%.

Typically during La Niña, winter-spring rainfall is above average over northern, central and eastern Australia. If La Niña does develop, climate models suggest it is unlikely to reach levels seen in the most recent event of 2010–12—one of the strongest La Niña events on record.