ENSO-neutral continued this past month, indicated in the mostly near average sea surface temperatures (SSTs) across the east-central and eastern equatorial Pacific Ocean [Fig. 1]. The most recent weekly Niño-3.4 index was +0.3°C, while SST anomalies remained cooler in the eastern Niño-3 region (-0.1°C) and warmer in the western Niño-4 region (+0.5°C; [Fig. 2]). Below-average subsurface temperatures weakened during the past month (area-averaged index in [Fig. 3]), but negative anomalies still dominated the eastern half of the Pacific [Fig. 4]. Low-level wind anomalies were easterly over the western equatorial 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.

Compared to the previous month, the most recent IRI plume delayed the emergence of La Niña to September-November 2024, with La Niña then persisting through the Northern Hemisphere winter [Fig. 6]. The forecast team is also favoring a delayed development of La Niña this month, but is anticipating the transition to occur earlier (August-October). This is, in part, supported by the continuation of below-average subsurface ocean temperatures and near-term forecasts suggesting a resurgence of easterly wind anomalies in July. In summary, ENSO-neutral is expected to continue for the next several months, with La Niña favored to emerge during August-October (70% chance) and persist into the Northern Hemisphere winter 2024-25 (79% 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 8 August 2024.

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