ENSO Outlook decreases to El Nino WATCH; positive Indian Ocean Dipole possible

21/05/2019

The Bureau of Meteorology's ENSO Outlook dial has been moved to "El Niño WATCH", meaning the chance of an El Niño forming in 2019 has been reduced to around 50 per cent, roughly twice the normal likelihood. The dial had previously been sitting at "El Niño ALERT", indicating the chances of an El Niño forming were closer to 70 per cent.

At present, sea surface temperatures in the tropical Pacific remain close to El Niño levels but water beneath surface has slowly cooled over the past few months. Atmospheric conditions have also remained neutral, despite short-term El Niño-like conditions.

International models surveyed by the Bureau indicate the sea surface temperatures in the tropical Pacific Ocean are likely to remain close to El Niño thresholds until mid-winter, before cooling in late winter to spring. By August, two of the eight models are clearly at El Niño levels, another two near El Niño thresholds, and the remaining models Neutral.

An El Niño typically brings drier than average conditions to eastern Australia during winter-spring, and warmer days across the southern two-thirds of the country.

The Indian Ocean Dipole, one of Australia's other main climate drivers remains neutral but the majority of international models surveyed by the Bureau indicate a positive IOD event is likely to develop in winter. A positive IOD typically means below average winter-spring rainfall for much of southern and central Australia.