Strongest El Niño since 1950? US climate centre gives 75% chance of historic event

The El Niño weather phenomenon has strengthened over the past month and is expected to intensify further through the end of the year, with the US National Oceanic and Atmospheric Administration’s Climate Prediction Centre forecasting more than a 90% chance of a very strong event during the Northern Hemisphere fall and winter, Reuters reported.

The September-February period is expected to see particularly strong El Niño conditions. The Climate Prediction Centre has estimated a 75% probability during October-December of a historic event that could surpass the strength of previous El Niño episodes recorded since 1950.

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The El Niño-Southern Oscillation index could exceed 2.5 degrees Celsius during the period, compared with the threshold of more than 2 degrees Celsius used to classify a very strong El Niño.

However, the centre cautioned that a stronger El Niño does not necessarily translate into proportionately stronger weather impacts. The intensity of the event can only increase the likelihood of certain impacts, it said, according to Reuters.

Ocean temperatures are also showing signs of a rapidly strengthening event. Sea surface temperature anomalies in the eastern equatorial Pacific exceeded 3 degrees Celsius over the past month, while subsurface waters remained significantly warmer than average. Atmospheric conditions, including unusual westerly winds and increased rainfall over the central and eastern Pacific, also pointed towards a strengthening El Niño.

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The Climate Prediction Centre forecasts El Niño-Southern Oscillation probabilities across nine overlapping three-month periods. The chances of a very strong El Niño are highest from September-November through November-January, before declining gradually.

For India, the development could have implications for weather and rainfall. El Niño is generally associated with hotter and drier conditions in India, while La Niña tends to support more favourable rainfall.