El Nino climate has developed. Oceanic El Nino is quite strong.

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Fig. 1: The 12-week monitor of the Nino SSTA regions indicates a steady moderate to strong El Nino although very warm waters off the northwest coast of South America have cooled slightly.

Discussion: Moderate to strong El Nino continues. The Nino34 SSTA is steady at +1.6C. (Fig. 1). The operational Nino index (ONI) which averages the last 3 months of Nino34 SSTA index, is +1.1C which is not as strong as the 1987, 1997, and 2015 strong El Nino episodes at this time of year. However, the current ONI is much stronger than the weaker El Nino episodes of 1991, 2002, 2004, 2006, 2009, and 2018. While the oceanic El Nino onset was in June, the atmospheric El Nino climate has lagged. Finally, southern oscillation index (SOI) is consistently negative (Fig. 2) and a full-throttle El Nino climate is developing now. A collection of dynamic and statistical Nino34 SSTA forecasts (by the International Research Institute for Climate and Society) indicates El Nino 2023-24 peaks in December and weakens toward neutral phase next May (Fig. 3).

Fig. 2: Oceanic El Nino formed last June. Atmospheric El Nino is slower to develop. The southern oscillation index is finally staying negative, and an El Nino climate is forming now.

Fig. 3: A collection of all dynamic and statistical Nino34 SSTA forecasts projecting ENSO into mid-2024.