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 (CFS03) 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 using linear inverse modeling (Penland and Magorian 1993: J. Climate, 6, 1067‑1076) are shown in Figs. F9 and F10. Predictions from the Scripps / Max Planck Institute (MPI) hybrid coupled model (Barnett et al. 1993: J. Climate, 6, 1545‑1566) are shown in Fig. F11.  Predictions from the ENSO‑CLIPER statistical model (Knaff and Landsea 1997, Wea. Forecasting, 12, 633‑652) are shown in Fig. F12.  Niño 3.4 predictions are summarized in Fig. F13, 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 Niño Watch

 

Outlook:

 

El Niño is expected to form and continue through the Northern Hemisphere winter 2018-19 (~90% chance) and through spring (~60% chance).

 

Discussion:  

 

ENSO-neutral continued during November, despite the continuation of above-average sea surface temperatures (SSTs) across the equatorial Pacific Ocean (Fig. T18). The monthly SST indices for all four Niño regions were near +1.0°C (Table T2). Positive subsurface temperature anomalies (averaged across 180°-100°W) weakened slightly, but above-average temperatures persist at depth across the central and eastern equatorial Pacific Ocean (Fig. T17). However, the atmospheric anomalies largely reflected intra-seasonal variability related to the Madden-Julian Oscillation (Fig. T12), and have not yet shown a clear coupling to the above-average ocean temperatures. For the month as a whole, atmospheric convection remained close to average near the Date Line and suppressed over Indonesia (Fig. T25).  Also, the low-level and upper level winds were mostly near average across the equatorial Pacific (Figs. T20, T21).  The equatorial Southern Oscillation index (SOI) was negative, while the traditional SOI was near zero (Table T2 and Fig. T2). Despite the above-average ocean temperatures, the overall coupled ocean-atmosphere system remained ENSO-neutral.

 

The majority of models in the IRI/CPC plume predict a Niño3.4 index of +0.5°C or greater to continue through the winter and spring (Figs. F1-F13). The official forecast favors the formation of a weak El Niño, with the expectation that the atmospheric circulation will eventually couple to the anomalous equatorial Pacific warmth.  In summary, El Niño is expected to form and continue through the Northern Hemisphere winter 2018-19 (~90% chance) and spring (~60% 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).