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HOME > Expert Assessments > Climate Diagnostics Bulletin > Forecast Forum
 
Forecast Forum - January 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 January negative equatorial SST anomalies less than –0.5ºC were observed at most locations between the date line and the South American coast, while anomalies greater than +0.5ºC were restricted to the region between Indonesia and 160ºE (Figs. T9 and T18).  Negative SST departures increased in magnitude in the Niño 4 and Niño 3.4 regions (Table T2 and Fig. T5), as the oceanic cold tongue strengthened in the central equatorial Pacific.

         During January above-average precipitation (negative OLR anomalies) was observed over Indonesia , the Philippines and northern Australia , while below-average precipitation (positive OLR anomalies) was observed over the central equatorial Pacific (Figs. T8 and T25). Stronger-than-average low-level (850-hPa) easterly winds (Figs. T7 and T13) persisted over the central equatorial Pacific, and anomalous upper-level (200-hPa) cyclonic circulation centers were observed in both hemispheres (Fig. T22).  Collectively, the present oceanic and atmospheric anomalies 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 November 2005 - January 2006 is -0.7°C, which indicates La Niña conditions. Over the past several months most of the statistical and coupled model forecasts have trended towards cooler conditions in the tropical Pacific through mid-2006.  The spread of the most recent statistical and coupled model forecasts (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 recent cooling trends in observed oceanic conditions support a continuation of La Nina 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 Indonesia (central equatorial Pacific) during the remainder of the NH winter. That pattern of tropical precipitation favors a northward shift in the position of the jet stream over the eastern North Pacific during winter, which is usually accompanied by drier-than-normal conditions over southern California and Arizona . The recent patterns of anomalous temperature and precipitation for the United States are similar to wintertime patterns observed during previous La Niña episodes, except for temperature over the northern Plains and in the Pacific Northwest .

          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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