La Nina weather, which brings heavy rains and floods to India, may develop in the next three months but it is expected to be relatively weak and short-lived, the World Meteorological Organization (WMO) has said.
Latest forecasts from WMO Global Producing Centres of Long-Range Forecasts indicate a 55 per cent likelihood of a transition from the current El Nino-Southern Oscillation (ENSO) neutral conditions to La Nina during December 2024 to February 2025, it said in its latest update on Wednesday.
However, the forecast is lower than its earlier update issued in September forecasting a 60 per cent likelihood of La Nina in December-February.
Contrasting outlook
The return of the ENSO-neutral conditions is favoured during February-April 2025, with about 55 per cent chance. The WMO forecast is in contrast to Australia’s Bureau of Meteorology prediction that ENSO will be neutral until April 2025 and conditions are not meeting La Nina thresholds.
WMO said naturally occurring climate events such as La Nina and El Nino events are taking place in the broader context of human-induced climate change, which is increasing global temperatures, exacerbating extreme weather and climate, and impacting seasonal rainfall and temperature patterns.
“The year 2024 started out with El Nino and is on track to be the hottest on record. Even if a La Nina event does emerge, its short-term cooling impact will be insufficient to counterbalance the warming effect of record heat-trapping greenhouse gases in the atmosphere,” WMO Secretary-General Celeste Saulo said.
Even in the absence of El Nino or La Nina conditions since May, an extraordinary series of extreme weather events has been witnessed, including record-breaking rainfall and flooding which have become the new norm in changing climate, she said.
Reason for slowdown
As of the end of November 2024, oceanic and atmospheric observations continued to reflect ENSO-neutral conditions which have persisted since May. Sea surface temperatures are slightly below average over much of the central to eastern equatorial Pacific.
However, this cooling has not yet reached typical La Niña thresholds. One possible reason for this slow development is the strong westerly wind anomalies observed for much September to early November 2024, which are not conducive for La Nina development.
The latest Global Seasonal Climate Updates (GSCU) indicates that widespread above-normal sea-surface temperatures are expected to persist in all ocean basins apart from the near-equatorial eastern Pacific Ocean (consistent with the predicted likely emergence of weak La Nina conditions). As a result, above-normal temperatures are predicted over almost all land areas.
Predictions for rainfall for December 2024 to February 2025 are consistent with the enhanced positive east to west sea surface temperature gradient typically observed during La Nina.
