Forecast Forum - June 2006

          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 Forecast System Model (CFS03) are presented in Figs. F3 and F4a, F4b.  Predictions from the Markov model (Xue, et al. 2000: J. Climate, 13, 849‑871) are shown in Figs. F5 and F6.   Predictions from the latest version of the LDEO model (Chen et al. 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 and Landsea 1997, Wea. Forecasting, 12, 633‑652) are shown in Fig. F12.  Niño 3.4 predictions are summarized in Fig. F13, 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

            ENSO-neutral conditions are expected to prevail during the next 3-6 months. 

Discussion

           The patterns of anomalous ocean temperatures and atmospheric circulation during June 2006 were consistent with ENSO-neutral conditions in the tropical Pacific.  Positive SST anomalies expanded eastward during the month, with SST anomalies greater than +0.5C observed in most of  the equatorial Pacific between 130ºE and 140ºW (Fig. T18).  As a result positive SST anomalies were observed in both the Niño 4 and Niño 3.4 regions, while anomalies remained near zero in the eastern equatorial Pacific (Niño 3 and Niño 1+2 regions) (Table T2 and Fig. T5).  The equatorial subsurface temperature anomaly pattern featured negative anomalies in the far eastern Pacific and positive anomalies in the western and central Pacific during June 2006 (Fig. T17).  Beginning in  February the area of positive anomalies at depth has expanded to the east (Fig. T15), and the basin-wide upper ocean heat content increased.  Low-level (850-hPa) and upper-level (200-hPa) winds over the tropical Pacific were near average during the month (Figs. T20 and T21). Collectively, these atmospheric and oceanic features indicate ENSO-neutral conditions.

           The value of the Oceanic Niño Index (ONI; 3-month running mean average of SST anomalies in the Niño 3.4 region – computed using the Extended Reconstructed SST version-2 data set) for April - June 2006 is 0.0°C, which indicates ENSO neutral conditions.  Most of the statistical and coupled models predict slightly positive SST anomalies (ENSO-neutral to weak El Niño) in the Niño 3.4 region through the end of 2006 (Figs. F1, F2, F3, F4a, F4b, F5, F6, F7, F8, F9, F10, F11, F12 and F13). These forecasts are consistent with the recent build up in upper-ocean heat content along the equator. Since the low-level easterlies have been near average, it seems likely that ENSO-neutral conditions will continue at least for the next three months. However, the spread of the forecasts (ENSO-neutral to El Niño) indicates considerable uncertainty in the outlook for late 2006 and early 2007.

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