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 Advisory

 

Outlook:

 

There is a greater than 90% chance that El Niño will continue through Northern Hemisphere fall 2015, and around an 85% chance it will last through the 2015-16 winter.

 

Discussion:  

 

            During May, sea surface temperatures (SST) anomalies increased across the central and eastern equatorial Pacific Ocean (Fig. T18).  All of the Niño indices were in excess of +1.0°C, with the largest anomalies in the eastern Pacific, indicated by recent weekly values of +1.4°C in Niño-3 and +1.9°C in Niño-1+2 (Table T2).  After a slight decline in April, positive subsurface temperature anomalies strengthened during May in association with the progress of a downwelling oceanic Kelvin wave (Fig. T17).  In addition, anomalous low-level westerly winds remained over most of the equatorial Pacific, and were accompanied by anomalous upper-level easterly winds (Figs.T20, T21). The traditional and equatorial Southern Oscillation Index (SOI) were both negative (Table T1 & Fig. T2), consistent with enhanced convection over the central and eastern equatorial Pacific and suppressed convection over Indonesia (Fig.T25).  Collectively, these atmospheric and oceanic features reflect an ongoing and strengthening El Niño.

Nearly all models predict El Niño to continue throughout 2015, with many predicting SST anomalies to increase into the late fall 2015 (Figs. F1-F13).  For the fall and early winter, the consensus of forecasters slightly favors a strong event (3-month values of the Niño-3.4 index +1.5°C or greater), relative to a weaker event. However, this prediction may vary in the months ahead as strength forecasts are the most challenging aspect of ENSO prediction.  A moderate, weak, or even no El Niño remains possible, though at increasingly lesser odds.  There is a greater than 90% chance that El Niño will continue through Northern Hemisphere fall 2015, and around an 85% chance it will last through the 2015-16 winter.

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