Potential Complete Reversal in ENSO Phase by July/August 2024

Fig. 1: The NCEP CFS V2 Nino34 SSTA favors a big change in 2024.  

Fig. 2: All forecast models are decelerating El Nino by April 2024.

Fig. 3: The current Nino SSTA regions over the past 12 weeks indicate a potential (warm) peak approaching of the Ninino34 SSTA zone.

Fig. 4: The upper ocean heat in the equatorial Pacific has increased and is now at peak for the 2023-24 El Nino episode.

Discussion: The latest NCEP CFS V2 Nino34 SSTA forecast continues to indicate an El Nino 2023-24 peak over the next 1-2 months followed by a steady weakening signature for the first half of 2024 to neutral ENSO mid-year (Fig. 1). The latest 8 ensemble members of the Nino34 SSTA forecast indicate a vigorous ENSO phase change to La Nina for JUL/AUG of 2024! A collection of Nino34 SSTA forecasts for April next year each indicate a weaker El Nino although the Australia Bureau of Meteorology maintains a strong warm ENSO episode (Fig. 2). Historically, stronger El Nino’s (as defined by Nino34 SSTA index) has tendency to flip to La Nina the following year. However, the anomalous warm oceans poleward of the tropics in 2023-24 and lack of a strong El Nino climate pattern to coincide with the robust El Nino oceanic signature suggests ENSO 2024 is likely uncertain. Currently, Nino34 SSTA is warming toward peak which occurs during the next 1-2 months (Fig. 3). The subsurface heat across the equatorial Pacific has reached the warmest signature so far for El Nino 2023-24 (Fig. 4).