MELBOURNE, Australia – The El Niño–Southern Oscillation (ENSO) remains neutral. With the tropical Pacific Ocean warmer than average, and around half the international climate models reaching El Niño levels later in the year, development of El Niño in 2017 cannot be ruled out.
The Bureau’s ENSO Outlook remains at El Niño WATCH, meaning there is around a 50% chance—double the normal likelihood—of El Niño developing in 2017.
Sea surface temperatures across the central tropical Pacific remained half a degree warmer than average over the past month. This is below the El Niño threshold of +0.8 °C. Further warming in the coming fortnight is unlikely, with trade winds forecast to be stronger than average. All other ENSO indicators are also neutral.
Five of eight international climate models suggest the tropical Pacific Ocean is likely to warm above El Niño thresholds during the second half of 2017.
However virtually all models now suggest less warming is likely to occur compared to their previous outlooks, indicating any event may be weak.
Models have lower accuracy forecasting El Niño during the autumn months, though accuracy begins to improve from June.
El Niño is often, but not always, associated with a drier than average winter–spring over eastern Australia. Even if El Niño thresholds are not met, Australia may still see some El Niño-like effects if waters in the tropical Pacific Ocean remain warm.
The Indian Ocean Dipole (IOD) remains neutral. Four out of six climate models suggest a positive IOD is likely to develop during winter. A positive IOD is typically associated with a drier than average winter–spring for southern and central Australia.
