Sea surface temperatures (SST) were above average across the equatorial Pacific Ocean [Fig. 1], increasing in the central and east-central Pacific during November. The growth in SST anomalies, however, abated in early December, with the latest weekly Niño index values at +1.4°C in Niño-4, +1.9°C in Niño-3.4, +2.0°C in Niño-3, and +1.3°C in Niño-1+2 [Fig. 2]. Area-averaged positive subsurface temperature anomalies increased significantly during November [Fig. 3], reflecting the strengthening of above-average subsurface temperatures in the central and eastern Pacific associated with a downwelling oceanic Kelvin wave [Fig. 4]. Low-level wind anomalies were westerly in the central and eastern Pacific, while upper-level wind anomalies were easterly across the Pacific. Convection/rainfall remained enhanced at the Date Line and was suppressed around Indonesia [Fig. 5]. The equatorial Southern Oscillation Index (SOI) and the station-based SOI were negative. Collectively, the coupled ocean-atmosphere system reflected a strong El Niño.

The most recent IRI plume favors El Niño to continue through the Northern Hemisphere winter 2023-24 [Fig. 6]. Based on the latest forecasts, there is now a 54% chance of a "historically strong" El Niño during the November-January season (≥ 2.0°C in Niño-3.4). An event of this strength would potentially be in the top 5 of El Niño events since 1950. While stronger El Niño events increase the likelihood of El Niño-related climate anomalies, it does not imply expected impacts will emerge in all locations or be of strong intensity (see CPC seasonal outlooks for probabilities of temperature and precipitation). In summary, El Niño is expected to continue through the Northern Hemisphere winter, with a transition to ENSO-neutral favored during April-June 2024 (60% chance; [Fig. 7]).

This discussion is a consolidated effort of the National Oceanic and Atmospheric Administration (NOAA), NOAA's National Weather Service, and their funded institutions. Oceanic and atmospheric conditions are updated weekly on the Climate Prediction Center web site (El Niño/La Niña Current Conditions and Expert Discussions). Additional perspectives and analysis are also available in an ENSO blog. A probabilistic strength forecast is available here. The next ENSO Diagnostics Discussion is scheduled for 11 January 2024.

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