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 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. 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.   Predictions from the ENSO-CLIPER statistical model (Knaff, J. A. and C. W. Landsea 1997, Wea. Forecasting, 12, 633-652) are shown in Fig. F10.

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 observed oceanic and atmospheric conditions and SST predictions, warm episode (El Niño) conditions are expected to continue during the remainder of 2002 and into early 2003.

Discussion

Based on the latest seasonally-averaged sea surface temperature (SST) data, a Pacific basin wide warm episode (El Niño) has now developed. During June 2002 SST anomalies increased to greater than +1°C throughout the equatorial Pacific between 170°E and 105°W (Fig. T18), and subsurface temperature anomalies increased throughout the central and east-central Pacific (Fig. T17). While positive SST anomalies in the vicinity of the date line (180°W) have gradually increased since mid-2001, those in the east-central portion of the basin (between 140°W and 105°W) gradually increased in early 2002 and rapidly increased during late May and early June 2002 (Fig. T9). For the first time since the end of the 1997-98 El Niño episode the Niño 3, Niño 3.4 and Niño 4 indices were all greater than +0.5°C during June (Table T2).

The Madden-Julian Oscillation (MJO) continues to be a major source of week-to-week and month-to-month variability in the atmospheric circulation of the Tropics and subtropics (Figs. T11, T12, T13). In spite of this variability, since March 2002 the SOI has been consistently negative (Table T1), with an average value of -0.8 during the last four months, and the low-level equatorial easterly winds have weakened over the central Pacific (140-175°W) (Fig. T13). The oceanic thermocline has deepened east of the date line (180°W) since mid-May (Fig. T15), consistent with the basin-wide weakening of the low-level equatorial easterly winds. Given the recent strength of the MJO and its period of about 40 days, it is likely that significant month-to-month fluctuations will continue to occur in many atmospheric indices used to monitor the ENSO cycle.

The oceanic and atmospheric variables discussed above reflect the presence of warm episode (El Niño) conditions. Most statistical and coupled model predictions (Figs. F1, F2, F3, F4, F5, F6, F7, F8, F9, F10) indicate that weak-to-moderate El Niño conditions will continue through the end of 2002 and into early 2003. It is important to add that a weak or moderate El Niño would feature much weaker global impacts than were experienced during the very strong 1997-98 El Niño.

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).