MELBOURNE, Australia – The El Niño – Southern Oscillation (ENSO) is neutral. However, model outlooks and recent warming in the Pacific Ocean mean there is an increased chance of El Niño forming later this year.
The ENSO Outlook of the Bureau of Meteorology of the Australian Government (BOM) is currently at El Niño WATCH, which means the likelihood of El Niño forming this year is around double the average chance at 50%.
Most atmospheric and oceanic indicators of ENSO are currently neutral. However, sea surface temperatures (SSTs) in the eastern Pacific Ocean have warmed since the start of the year, and the Southern Oscillation Index (SOI) has been trending downwards.
While these are fairly typical changes in the lead up to El Niño, trade winds and cloudiness have not shown any significant shift away from neutral.
All eight international models surveyed by the Bureau show steady warming of the central tropical Pacific Ocean over the next six months. Six models suggest El Niño thresholds may be reached by July 2017.
However, some caution must be taken, as models have lower accuracy when forecasting through the autumn months than at other times of the year.
El Niño is often, but not always, associated with below average winter–spring rainfall over eastern Australia and warmer than average winter–spring maximum temperatures over the southern half of Australia.
The Indian Ocean Dipole (IOD) has little influence on Australia from December to April. Current outlooks suggest a neutral IOD is likely to remain at least through to the end of winter.