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:

 

There is a 50-55% chance of El Niño onset during the Northern Hemisphere fall 2018 (September-November), increasing to 65-70% during winter 2018-19.

 

Discussion:  

 

ENSO-neutral continued during August, as indicated by a blend of slightly above- and below- average sea surface temperatures (SSTs) across the equatorial Pacific Ocean (Fig. T18). Over the last month, the westernmost Niño-4 region was the warmest (monthly average was +0.5°C), while the Niño-3 and Niño-3.4 regions were weakly positive (Table T2). Subsurface temperature anomalies (averaged across 180°-100°W) were positive, with an increase in above-average subsurface temperatures in the central Pacific and a slight expansion of negative anomalies in the eastern Pacific (Fig. T17). Convection returned to near average over the Date Line, and was slightly enhanced over Indonesia (Fig. T25). Low-level westerly wind anomalies re-developed across the east-central and western Pacific, although they were only slightly evident in the monthly average (Fig. T20). Upper-level wind anomalies were westerly over the eastern Pacific (Fig. T21). Overall, the oceanic and atmospheric conditions reflected ENSO-neutral. 

 

The majority of models in the IRI/CPC plume continue to predict the onset of El Niño sometime during the Northern Hemisphere fall and continuing through the winter (Figs. F1-F13). The forecasters also favor El Niño formation during the fall, and are leaning toward the more conservative model guidance that indicates a weak El Niño event. The persistence of above-average subsurface temperatures and continuing flare-ups of westerly wind anomalies also support the eventual development of El Niño. In summary, there is a 50-55% chance of El Niño onset during the Northern Hemisphere fall 2018 (September-November), increasing to 65-70% during winter 2018-19.

 

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