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 ocean/atmosphere model (Ji et al. 1998, Mon. Wea. Rev, 126, 1022-1034) are presented in Figs. F3 and F4. Predictions from the latest version of the LDEO model (Chen, D., M. A. Cane, S. E. Zebiak, Rafael Canizares and A. Kaplan, 2000, Geophys. Res. Let., accepted) are shown in Figs. F5 and F6. Predictions using linear inverse modeling (Penland and Magorian 1993, J. Climate, 6, 1067-1076) are shown in Figs. F7 and F8. Predictions from the Scripps / Max Planck Institute (MPI) hybrid coupled model (Barnett et al. 1993, J. Climate, 6, 1545-1566) are shown in Fig. F9.

A gradual weakening of cold episode (La Niña) conditions is likely over the next 6 months, with near-normal or slightly cooler-than-normal conditions in the tropical Pacific by the end of the year.

The large-scale oceanic and atmospheric circulation patterns continued to reflect cold episode conditions in the tropical Pacific during May. Cold episode-related oceanic features included below normal SSTs (negative anomalies greater than -1°C) in the central and west-central equatorial Pacific (Fig. T18), and above- (below-) normal subsurface temperatures in the western (eastern) equatorial Pacific (Fig. T17). Related atmospheric features included stronger-than-normal low-level easterly winds over the western tropical Pacific (Fig. T20), above-normal precipitation over Indonesia (Fig. T25), and suppressed rainfall over the western equatorial Pacific (Fig. T25). These patterns of anomalous low-level winds and convection have been highly persistent since late 1998 (Figs. T7 and T8), consistent with ongoing cold episode conditions.

The most recent NCEP statistical and coupled model forecasts, as well as other available forecasts, exhibit considerable spread in the evolution of the tropical Pacific SSTs over the next 3-9 months. The NCEP coupled model forecast (Figs. F3 and F4) and the LDEO forecast (Figs. F5 and F6) indicate that cold episode conditions will weaken during the next 3 months, followed by near-normal conditions through the end of the year. The NCEP statistical model forecast (Figs. F1 and F2) and other available coupled model and statistical model predictions (Figs. F7, F8, F9) indicate the continuation of cold episode conditions through the end of 2000, with a return to near-normal conditions early in 2001. The lack of any rapid evolution in the subsurface thermal structure and the persistence of low-level easterly anomalies over the central and western equatorial Pacific continues to support a slower decay of cold episode conditions than is shown by either the NCEP coupled model or the LDEO model.