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HOME > Expert Assessments > Climate Diagnostics Bulletin > Forecast Forum
Forecast Forum - October 2002

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.

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


Based on the observed oceanic and atmospheric conditions and the SST predictions, warm episode (El Niño) conditions are expected to continue through the spring of 2003.


Further evolution toward basin-wide mature El Niño conditions occurred during October. SST anomalies (departures from average) were greater than +1°C throughout most of the equatorial Pacific between 180°W and the South American coast during the month (Fig. T18), and positive subsurface temperature departures (Fig. T17) and a deeper-than-average oceanic thermocline (Figs. T15 and T16) prevailed throughout most of the equatorial Pacific.

The current warm episode has also exhibited a number of typical atmospheric features in recent months. The Southern Oscillation Index (SOI) has been consistently negative since March 2002 (Table T1), and weaker-than-average low-level easterly winds have been observed throughout the tropical Pacific since May 2002 (Fig. T7). Consistent with this, there has been a reversal of the east-west Walker circulation in the Pacific-Indonesian sector, with mean descending air motion over Indonesia and ascending air motion over the central and east-central equatorial Pacific (Fig. T29). During October the anomalous circulation in the tropical Pacific was accompanied by wetter-than-average conditions over the tropical Pacific, especially in the vicinity of the date line (180°W), and drier-than-average conditions over Indonesia (Figs. E3 and E4). These oceanic and atmospheric features indicate the presence of El Niņo.

Most coupled model and statistical model forecasts indicate that El Niņo conditions will continue into the spring of 2003 (Figs. F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11, F12). Thereafter the forecasts are more uncertain, during a time of the year when all of the techniques have difficulty in making skillful forecasts. Based on the recent evolution of conditions in the tropical Pacific, we expect SST anomalies to increase further in the eastern equatorial Pacific (Niņo 3 and Niņo 1+2 regions), with the establishment of basin-wide mature El Niņo conditions during December 2002-February 2003. Furthermore, based on the latest predictions and an assessment of current oceanic and atmospheric conditions, we expect that this event will be weaker than the 1997-98 El Niņo. Thus, the global impacts should generally be weaker than those observed during 1997-98. However, strong impacts are still possible in a few locations.

Expected global impacts include: 1) drier-than-average over Indonesia and eastern Australia continuing during the next several months, 2) wetter-than-average over southeastern South America (Uruguay, northeastern Argentina, and southern Brazil) during the next three months, 3) drier-than-average over southeastern Africa during December 2002-February 2003, 4) drier-than-average over Northeast Brazil and northern South America during December 2002-April 2003, and 4) wetter-than-average conditions over coastal sections of Ecuador and northern Peru during December2002-April 2003. Over the United States and Canada we expect: 1) drier-than-average conditions in the Ohio Valley states and northern Rockies during winter 2002-2003, 2) wetter-than-average conditions along much of the southern tier of the U.S. during winter 2002-2003, and 3) warmer-than-average conditions in the northern tier states, southern and southeastern Alaska, and western and central Canada during late fall 2002 and winter 2002-2003.

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

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