La Niña weather will likely develop in coming months but it could be relatively weak (in terms of the magnitude of the sea surface temperatures anomaly) and short-lived, Australia’s Bureau of Meteorology, said on Tuesday.
“The latest model forecasts are now more aligned than they have been in recent months, with a clearer shift toward La Niña levels,” it said in its Climate Driver update.
BoM’s model suggests that sea surface temperatures (SSTs) are likely to remain within the El Nino-Southern Oscillation (ENSO) neutral range (−0.8 °C to +0.8 °C ) throughout the forecast period (October-December 2024).
“Three of 7 climate models suggest the possibility of SSTs in the tropical Pacific exceeding the La Niña threshold (below −0.8°C) from October, and another 3 models forecast SSTs close to the threshold,” the Australian weather agency said.
Meanwhile, one of the models indicates negative Indian Ocean Dipole, (IOD) also known as Indian Nino, during October and November. However, BoM said, “Most climate models indicate the IOD is likely to remain neutral, but slightly negative, for the rest of the year.”
The Australian weather agency said the sustained nature of the near-record global ocean heat between April and August suggests that climate patterns such as ENSO and IOD may not necessarily behave or evolve as they have in the past.
Meanwhile, the US weather agency Climate Prediction Centre (CPC), an arm of the National Oceanic and Atmospheric Administration (NOAA), has reiterated its view that La Niña is favoured to emerge during September-November (71 per cent chance). It is expected to persist through January-March 2025.
“Since late August 2024, negative OLR anomalies (enhanced convection/rainfall) have persisted near Indonesia and the western Pacific Ocean,” CPC said.
This probably explains India receiving surplus rains in August and September. In the first half of September, the country has received 14 per cent surplus rain. Overall, during the current south-west monsoon (which set in on May 30), there has been 8 per cent excess rainfall.