ENSO-neutral continued during July 2024, with near-average sea surface temperatures (SSTs) observed across most of the equatorial Pacific Ocean [Fig. 1]. In the past week, except for the Niño-4 index (+0.3°C), the other Niño region indices were slightly negative [Fig. 2]. Below-average subsurface temperatures strengthened during the past month (area-averaged index in [Fig. 3]) associated with the expansion of negative anomalies along the thermocline [Fig. 4]. Low-level wind anomalies were easterly over the east-central and eastern Pacific, and upper-level winds were westerly over the eastern Pacific. Convection was near average around Indonesia and the Date Line [Fig. 5]. Collectively, the coupled ocean-atmosphere system reflected ENSO-neutral.

The IRI plume indicates that Niño-3.4 is most likely to be below La Niña thresholds for four overlapping seasons, from September-November 2024 through December 2024 - February 2025 [Fig. 6]. Based on updated guidance and recent observations, the forecast team predicts nearly equal chances for ENSO-neutral and La Niña in August-October 2024, with higher odds for La Niña in September-November. Although the rate of SST cooling has been slower than previously anticipated, below-average subsurface temperatures and low-level easterly wind anomalies remain conducive to La Niña development in the coming months. In summary, ENSO-neutral is expected to continue for the next several months, with La Niña favored to emerge during September-November (66% chance) and persist through the Northern Hemisphere winter 2024-25 (74% chance during November-January; [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 12 September 2024.

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