BOM, 12 August 2014
The Pacific Ocean has shown some renewed signs of El Niño development. Some warming has occurred in the central and eastern equatorial Pacific Ocean in the recent fortnight, due to a weakening of the trade winds. If the trade winds remain weak, more warming towards El Niño thresholds is possible.
The Bureau’s ENSO Tracker remains at WATCH status. This means the chance of an El Niño developing in 2014 is at least 50%, which is double the normal likelihood of an event. Five of the eight climate models surveyed by the Bureau suggest El Niño is likely for spring. However, if El Niño were to occur, it is unlikely to be a strong event.
El Niño is often associated with below-average rainfall over southern and eastern inland areas of Australia and above-average daytime temperatures over southern Australia. Similar impacts regularly occur prior to the event becoming fully established.
The Indian Ocean Dipole (IOD) index has been below −0.4 °C (the negative IOD threshold) since mid-June, which means 2014 is now considered a negative IOD year. Model outlooks suggest this negative IOD event is likely to be relatively short-lived, with the Indian Ocean returning to neutral by spring. A negative IOD pattern typically brings wetter winter and spring conditions to inland and southern Australia, and could be countering the effects of the current El Niño-like ocean pattern in the Pacific.