The Bureau of Meteorology (BoM) has raised its ENSO Outlook to “La Niña alert,” which means there is roughly a 70% chance of La Niña occurring. And if it does occur, it is expected that it will be weak and short-lived – unlike the La Niña experienced in Australia in 2010-12.
Oceanic indicators of ENSO show a current progression towards La Niña, with sea surface temperatures a few degrees shy of La Niña thresholds. Atmospheric indicators such as the Southern Oscillation Index (SOI) and trade winds, meanwhile, also indicate signs of shifting into a La Niña state.
The weather bureau said all international climate models suggest that the tropical Pacific will continue to cool down. All models will reach La Niña thresholds in December, and most will maintain these values until February.
Unlike the typical above-average rainfall associated with La Niña, the atypical sea surface temperature patterns in the Indian Ocean and closer to Australia reduce the likelihood of widespread summer rainfall. La Niña may also mean higher chances of prolonged warm spells for southeast Australia.
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BoM predicts a 50% chance of La Niña
