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HOME > Expert Assessments > Climate Diagnostics Bulletin > Forecast Forum
 
Forecast Forum - January  2003
 

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.

Outlook

Based on the recent evolution of conditions in the tropical Pacific and on coupled model and statistical model forecasts, warm episode (El Niņo) conditions are expected to continue to weaken through April 2003, followed by a return to near-normal conditions during May-October 2003.

Discussion

Warm episode (El Niņo) conditions continued during January 2003, as equatorial SST anomalies remained greater than +1°C in the central equatorial Pacific between 175°E and 125°W (Fig. T18). In addition, enhanced precipitation and cloudiness were observed over the central tropical Pacific (Figs. T25, E3, E4), and positive subsurface temperature departures (Fig. T17) and a deeper-than-average oceanic thermocline (Figs. T15 and T16) were observed throughout the equatorial Pacific east of 180°W. These conditions are consistent with mature warm episode conditions.

During January 2003 there were indications that the warm episode is beginning to weaken. Sea surface temperature anomalies decreased throughout the eastern equatorial Pacific by as much as 1.5°C during the month (Fig. T5), while equatorial easterly winds were near normal throughout the central and eastern equatorial Pacific (Fig. T7 and T20). Over the past several weeks there has also been a steady eastward progression of negative subsurface temperature anomalies (Figs. T15 and T17), indicating a gradual depletion of the excess warmth in the upper ocean of the equatorial Pacific. This evolution is typical during the mature phase of warm episodes.

Recent values of atmospheric and oceanic indices, such as the SOI, 850-hPa zonal winds index, Niņo 3.4, Niņo 3, and Niņo 1+2 are all considerably less in magnitude than those observed during the 1997/98 El Niņo (Figs. T1, T2, T3, T4, T5). The warming associated with the current event has been greatest in the central equatorial Pacific (Niņo 4 and Niņo 3.4 regions). Regions farther east (e.g., Niņo 3 and especially Niņo 1+2) have warmed much less.

Consistent with current conditions and recent observed trends, most coupled model and statistical model forecasts indicate that El Niņo conditions will continue to weaken through April 2003 (Figs. F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11, F12). Thereafter the consensus forecast is for near-normal conditions during May-October 2003. Those areas of the world usually affected by El Niņo may continue to experience related impacts during the next 2-3 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).


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