Late season El Niño remains possible

ENSO status graph, stages are La Niña WATCH, La Niña ALERT, LA NIÑA, NEUTRAL, El Niño WATCH, El Niño ALERT, El NIÑOsource: BoM El Niño Wrap-Up, 23 September

Despite most ocean and atmospheric indicators falling short of El Niño thresholds, model outlooks and recent observations indicate that a late El Niño remains possible. The Bureau’s ENSO Tracker indicates there is at least a 50% chance of El Niño developing over the coming months, which is double the long-term likelihood.

The Southern Oscillation Index (SOI) has now remained negative for several weeks, and some renewed warming has occurred across the equatorial Pacific Ocean over the past fortnight. Both support the possibility of El Niño becoming established in the months ahead. Six of the eight international climate models surveyed by the Bureau indicate El Niño, or near-El Niño, conditions are likely for the southern summer.

El Niño is often associated with below-average rainfall over large parts of southern and eastern inland areas of Australia and above-average daytime temperatures over southern Australia. Such impacts can often occur while an event is developing, as experienced in some locations over the past several months.

The Indian Ocean Dipole (IOD) in the tropical Indian Ocean continues to show signs that it has returned to a neutral state. Waters to the north of Australia and in the Timor Sea are now at near-average temperatures. All climate models surveyed by the Bureau indicate the IOD will continue to weaken, with neutral conditions likely to become well established during the coming months.

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