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HOME > Expert Assessments > Climate Diagnostics Bulletin

Forecast Forum - July 2000

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.

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


Near-normal conditions are expected in the tropical Pacific through early 2001.


Cold episode (La Niņa) conditions continued to weaken during July, with near-normal oceanic and atmospheric conditions by the end of the month. Negative SST anomalies continued to weaken across the central tropical Pacific during July (Figs. T9, T18). The oceanic thermocline remained deeper-than-normal in the equatorial west-central and western Pacific (Fig. T15), with temperatures averaging up to 4°C above normal at thermocline depth (Fig. T17). The negative temperature anomalies that have characterized the subsurface thermal structure in the eastern Pacific since late 1998 weakened during July (Figs. T15, T17). The recent evolution of the oceanic thermocline and subsurface temperature anomalies is similar to that observed during 1999, with the major difference being an increase in the magnitude of the positive subsurface temperature anomalies in the western Pacific and a decrease in the magnitude of the negative anomalies in the eastern Pacific.

The pattern of tropical convection [as inferred from anomalous outgoing longwave radiation (OLR)] remained consistent with weak cold episode conditions during the month, with suppressed convection over the western and central equatorial Pacific (Fig. T25). However, consistent with the decrease in magnitude of the negative SST anomalies across the central equatorial Pacific in recent months, the low-level easterly wind anomalies across the central and western tropical Pacific have decreased in intensity (Figs. T7, T20).

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 near-normal conditions into early next 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 gradual weakening of negative SST anomalies through early 2001.

Weekly updates of SST, 850-hPa wind and OLR are available on the Climate Prediction Center homepage at: (Weekly Update).

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