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El Nino Outlook – September 2018

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Will an El Nino take place?

Current forecasts of Eastern Pacific sea surface temperatures (SST) and expert judgement point to a significant likelihood of an El Nino materializing: currently this stands at 50-55% chance of it happening in the northern hemisphere Autumn and 65-70% chance of it developing in the coming Winter.

How long is it likely to last?

Judging from the forecasts for how SST are likely to evolve, this El Nino, should it materialize, is likely to be relatively short and over by mid 2019.

How intense is it likely to be?

Based on the same evidence, and other features of the Pacific ocean circulation, it is likely to remain a weak to moderate El Nino.

How would it compare to the 2015-2016 event?

Currently we expect it to be weaker and much shorter than the 2015-16 event. This was one of the longest and most intense on the record – it started in late 2014, got really going in early 2015 and lasted until mid 2016.

Nothing to worry about, then?

Not exactly. Although we do not expect impacts on the scale of 2015-16, the link between El Nino intensity and impacts is not very strong. Weak El Nino in the past have led to significant droughts in specific regions. And we need to account for the heightened vulnerability of some regions due to past droughts or non climatic factors such as conflict