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HOME > Expert Assessments > Climate Diagnostics Bulletin > Forecast Forum
 
Forecast Forum - February 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

            La Niña conditions are expected to continue during the next 3-6 months.

 

Discussion

         

           The patterns of anomalous ocean temperatures, atmospheric circulation and precipitation are consistent in indicating La Niña conditions in the tropical Pacific. During February negative equatorial SST anomalies less than –0.5ºC were observed at most locations between 165ºE and 115ºW, while anomalies greater than +0.5ºC were restricted to the region between Indonesia and  155ºE and in the eastern equatorial Pacific between  100ºW and the South American coast (Fig. T18). Negative SST departures were observed in all of the Niño regions, except for Niño 1+2 (Table T2 and Fig. T5). During February, SST anomalies increased in the extreme eastern equatorial Pacific  (Fig. T9) and heavy rains occurred in some portions of Ecuador and northern Peru (Fig. T25). Brief warming has been observed at this time of the year in that region in previous years, including during the cold (La Niña) episodes of 1999, 2000 and 2001.

           During February above-average precipitation (negative OLR anomalies) was observed over portions of Indonesia , the Philippines and along the South Pacific Convergence Zone (SPCZ), while below-average precipitation (positive OLR anomalies) was observed over the central equatorial Pacific (Fig. T25). Stronger-than-average low-level (850-hPa) easterly winds (Figs. T7 and T20) persisted over the central equatorial Pacific, and anomalous upper-level (200-hPa) cyclonic circulation centers were observed in both hemispheres (Fig. T22). The equatorial subsurface temperature anomaly pattern (negative anomalies in the central and eastern Pacific and positive anomalies in the western Pacific) persisted during January 2006 (Figs. T15 and T17), and the basin-wide upper ocean heat content remained below-average.  Collectively, these atmospheric and oceanic features are consistent with La Niña conditions in the tropical Pacific.

         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 December 2005 - February 2006 is -0.8°C, which indicates La Niña conditions. Most of the statistical and coupled model forecasts indicate cooler-than-average conditions in the tropical Pacific through mid-2006.  The spread of the most recent forecasts (weak La Niña to ENSO-neutral) indicates some uncertainty in the outlooks (Figs. F1, F2, F3, F4a, F4b, F5, F6, F7, F8, F9, F10, F11, F12 and F13). However, current conditions (stronger-than-average easterly winds over the central equatorial Pacific and below-average upper-ocean heat content) and recent trends in observed oceanic conditions support continuation of La Niña conditions in the tropical Pacific during the next 3-6 months. Based on current conditions in the tropical Pacific, the most recent SST predictions, and on results from historical studies on the effects of cold episodes, we expect wetter-than-normal (drier-than-normal) conditions to prevail over northern Indonesia and the Philippines (central equatorial Pacific) during the next three months.

          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/

 


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