Forecast Forum

The canonical correlation analysis (CCA) forecast of SST in the central Pacific (Barnett et al. 1988, Science, 241, 192‑196; Barnston and Ropelewski 1992, J. Climate, 5, 1316‑1345), is shown in Figs. F1 and F2. This forecast is produced routinely by the Prediction Branch of the Climate Prediction Center. The predictions from the National Centers for Environmental Prediction (NCEP) Coupled Forecast System Model (CFSv2) are presented in Figs. F3 and F4a, F4b.  Predictions from the Markov model (Xue, et al. 2000: J. Climate, 13, 849‑871) are shown in Figs. F5 and F6.   Predictions from the latest version of the LDEO model (Chen et al. 2000: Geophys. Res. Let., 27, 2585‑2587) are shown in Figs. F7 and F8.  Predictions from the ENSO‑CLIPER statistical model (Knaff and Landsea 1997, Wea. Forecasting, 12, 633‑652) are shown in Fig. F9.  Niño 3.4 predictions are summarized in Fig. F10, provided by the Forecasting and Prediction Research Group of the IRI.

The CPC and the contributors to the Forecast Forum caution potential users of this predictive information that they can expect only modest skill.

 

ENSO Alert System Status: El Nino Advisory/ La Nina Watch

 

Outlook: A transition from El Nino to ENSO-neutral is likely in the next month.  La Nina may develop in June-August (49% chance) or July-September (69% chance).

 

Discussion:

 

During April 2024, below-average equatorial sea surface temperatures (SSTs) emerged in small regions of the eastern Pacific Ocean. However, above-average SSTs prevailed across the rest of the equatorial Pacific (Fig. T18). The monthly Niño index values remained between +0.6C and +0.8C in all regions, except for Nino-1+2 which was +0.1C (Table T2). Below-average subsurface temperatures held steady during the month, with negative anomalies extending from the Date Line to the eastern Pacific Ocean (Fig. T17). Low-level wind anomalies were easterly over the western equatorial Pacific, while upper-level winds were near average (Figs. T20 & T21).  Convection was near average overall across the equatorial Pacific Ocean and Indonesia (Fig. T25). Collectively, the coupled ocean-atmosphere system reflected the continued weakening of El Nino and transition toward ENSO-neutral.

The most recent IRI plume favors an imminent transition to ENSO-neutral, with La Nina developing during July-September 2024 and then persisting through the Northern Hemisphere winter (Figs. F1-F12).  The forecast team continues to favor the dynamical model guidance, which suggests La Nina could form as early as June-August 2024, with higher confidence of La Nina during the following seasons. La Nina generally tends to follow strong El Nino events, which also provides added confidence in the model guidance favoring La Nina. In summary, a transition from El Nino to ENSO-neutral is likely in the next month.  La Nina may develop in June-August (49% chance) or July-September (69% chance).

Weekly updates of oceanic and atmospheric conditions are available on the Climate Prediction Center homepage (El Niño/La Niña Current Conditions and Expert Discussions).