Chance for La Nina to emerge has decreased, says Australia’s BoM
Chances are bleak for the La Nina weather to emerge at least until February, the Australian Bureau of Meteorology (BoM) said today.
“The chance of a La Niña event developing in the coming months has decreased compared to recent outlooks. If a La Niña were to develop, it is forecast to be relatively weak (in terms of the strength of the sea surface temperature (SST) anomaly) and short-lived, with all models forecasting neutral values in February,” BoM said in its latest Climate Driver Update.
The weather agency’s model suggests that SSTs are likely to remain within the ENSO-neutral thresholds (−0.8 °C to +0.8 °C) throughout its forecast period to February 2025.
Of the six other climate models surveyed, four also suggest SSTs will remain within the El Nino-Southern Oscillation (ENSO) neutral thresholds.
Weak, inconsistent signals
Only one model suggests SSTs in the tropical Pacific are likely to exceed the La Niña threshold (below −0.8 °C) during November-January. Another model forecasts SSTs to briefly exceed the threshold, but only during December and January.
ENSO is neutral with both SSTs in the central equatorial Pacific Ocean and atmospheric patterns at ENSO-neutral levels. Atmospheric indices, such as those related to patterns of surface pressure, cloud and trade winds, are broadly consistent with an ENSO-neutral state. Although some have displayed La Niña-like signals over the past several weeks, these signals have not been consistent, said BoM.
The Australian weather agency said the Indian Ocean Dipole (IOD) is currently neutral, despite the weekly IOD index value (−0.58 °C) dropping below the negative IOD threshold (−0.40 °C) in the week ending October 13.
IOD to be neutral
All models indicate that the IOD is likely to remain neutral, but weakly negative, for the rest of the year. Forecasts indicate a sustained period of negative values is unlikely, but due to fluctuations in the tropical Indian Ocean SST patterns, the IOD index may drop, briefly, below the negative IOD threshold, it said.
Global SSTs remain at near-record levels, with temperatures since July being just short of the record temperatures observed during 2023. Yet, they are well above all other years since observations began in 1854.
The sustained nature of this significant global ocean heat suggests that climate indicators such as ENSO and IOD may not necessarily behave or evolve as they have in the past, it cautioned.
For India, prospects look good from the outlook as the country will unlikely go through any unseasonal weather pattern.