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 F4a, F4b.  Predictions from the Markov model (Xue, Y., A. Leetmaa, and M. Ji, 2000: ENSO prediction with Markov model: The impact of sea level. J. Climate, 13, 849-871) are shown in Figs. F5 and F6.   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., 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, J. A. and C. W. Landsea 1997, Wea. Forecasting, 12, 633-652) are shown in Fig. F12.  Niño 3.4 predictions are summarized in F13, which is 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.

Outlook

Based on current conditions and recent observed trends, it appears likely that cold episode (La Niña) conditions will develop in the tropical Pacific during the next several months.

Discussion

Warm episode (El Niño) conditions rapidly dissipated in the tropical Pacific during March and April 2003. Sea-surface temperature anomalies continued to decrease across the central and eastern equatorial Pacific during the month (Table 2, Figs. T5 and T9), while low-level equatorial easterlies continued to strengthen (Figs. T7 and T20). During April SST’s were below normal over a large portion of the east-central and eastern tropical Pacific (Fig. T18). During the past several months the depth of the oceanic thermocline has steadily decreased across the central and eastern equatorial Pacific, consistent with the appearance of colder than normal subsurface water in the upper ocean of the equatorial Pacific (Figs. T15 and T17).

The latest statistical and coupled model forecasts indicate considerable uncertainty for the next several months (Figs. F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11, F12, F13). While some forecast the possibility that La NiZa will develop during the second half of 2003, others indicate a resurgence of El Niño conditions by the end of the year. All such models have relatively low skill during the transition phases of the ENSO cycle. However, based on current conditions and recent observed trends, it appears likely that cold episode (La Niña) conditions will develop in the tropical Pacific during the next several months.

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