The Bureau of Meteorology has today issued a La Niña Alert, increasing the likelihood that they will officially declare a third consecutive La Niña event later this year.

After two back-to-back La Niña events between September 2020 and June 2022, the Pacific Ocean has been a neutral state, albeit close to La Niña thresholds, for the last two months.

However, all oceanic and atmospheric indicators used to monitor the Pacific Ocean have been trending towards La Niña levels in the past few weeks, indicating that La Niña may be re-emerging for a third consecutive year.

Today’s La Niña Alert from the Bureau means that there is a 70 percent chance that they will declare a La Niña event in the coming months.

The increasing likelihood of La Niña is also being closely monitored by other international climate agencies, including the U.S. climate Prediction Centre (CPC) and the Japanese Meteorological Agency (JMA). However, it is worth noting that both the CPC and JMA use different thresholds than the BoM to define La Niña. So, while the BoM declared the end of La Niña in June 2022, the JMA and CPC both classified an ongoing La Niña through the middle of this year, which is now gaining more strength.

Regardless of the definition used to classify La Niña, all signs are now pointing towards a re-emerging La Niña pattern in the Pacific Ocean. This trend if likely to continue in the months ahead, with the BoM, NOAA and JMA all giving a 60 to 80 percent chance of La Niña occurring during Southern Hemisphere’s spring.

Image: El Niño-Southern Oscillation (ENSO) forecast for the next 9 months, according to the U.S. CPC/IRI. The blue bars show the probability of La Niña occurring during each three-month period, with grey and red bars representing the probability of neutral and El Niño, respectively. Source: CPC/IRI

Image: ENSO forecast for November 2022 from seven different international models, based on the Nino-3.4 temperature anomaly, with five of seven modles predicting La Niña. Source: Bureau of Meteorology, issued on August 16.

Image: the JMA’s ENSO forecast for the rest of 2022, with a 60 percent chance of La Niña over the coming months. Source: JMA, issued on August 10.

La Niña increases the likelihood of above average rain and below-average daytime temperatures over large areas of northern and eastern Australia during spring. With the landscape still holding a lot of water from the first half of 2022, flooding will be an elevated risk over eastern and southeastern Australia in the next few months.