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 ocean/atmosphere model (Ji et al. 1998, Mon. Wea. Rev, 126, 1022-1034) are presented in Figs. F3 and F4. Predictions from the Cane and Zebiak model (Cane et al. 1986, Nature, 321, 827-832; Zebiak and Cane 1987, Mon. Wea. Rev., 115, 2262-2278) are shown in Figs. F5 and F6. Predictions from the modified Cane and Zebiak model (Chen et al. 1998, Geophys. Res. Let., 103, 2387-2840), referred to in the figures as LDEO3, 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.

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

Discussion and Outlook

Although cold-episode conditions have weakened substantially since the beginning of the year, the overall patterns of oceanic temperature and atmospheric circulation in June were similar to those observed during recent months. During June weak negative SST anomalies (Fig. T18) and weaker-than-normal convection (Fig. T25) prevailed throughout the equatorial Pacific east of 160°E , and low-level easterlies remained stronger than normal between 150°E and 160°W (Fig. T20).

Consistent with these features, the thermocline has been deeper than normal in the western equatorial Pacific and shallower than normal in the eastern equatorial Pacific. This has resulted in a dipole pattern of positive/ negative subsurface temperature anomalies in the western/ eastern equatorial Pacific (Fig. T17). The lack of any significant eastward shift in the positive subsurface temperature anomalies in the west-central equatorial Pacific indicates that the present cold episode is likely to continue for the next several months. This assessment of the situation is supported by the most recent NCEP coupled model forecasts (Figs. F3 and F4) and other available coupled model and statistical predictions that indicate cold episode conditions persisting through the end of 1999 and into the early part of 2000.

Weekly updates for SST, 850-hPa wind, and OLR are available on the Climate Prediction Center homepage at: http://www.cpc.ncep.noaa.gov (Weekly Update).