Forecast Forum

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.

 

ENSO Alert System Status:  La Niña Advisory

 

 

Outlook:

 

           La Niña conditions are expected to gradually strengthen and continue through the Northern Hemisphere winter 2011-12.

 

Discussion: 

 

During September 2011, La Niña conditions strengthened as indicated by increasingly negative sea surface temperature (SST) anomalies across the eastern half of the equatorial Pacific Ocean (Fig. T18).  The monthly Nino indices continued their cooling trend and all are currently at or below –0.6°C (Table T2).  Consistent with this cooling, the oceanic heat content (average temperatures in the upper 300m of the ocean) remained below-average in response to a shallower thermocline across the eastern Pacific Ocean (Fig. T17).  Also, convection continued to be suppressed near the Date Line, and became more enhanced near Papua New Guinea (Fig. T25).  In addition, anomalous low-level easterly and upper-level westerly winds persisted over the central tropical Pacific (Figs. T20, T21).  Collectively, these oceanic and atmospheric patterns reflect the continuation of La Niña conditions.  

Currently, La Niña is not as strong as it was in September 2010.  Roughly one- half of the ENSO models predict La Niña to strengthen during the Northern Hemisphere fall and winter (Figs. F1-F13), although most of these  maintain a weak La Niña   through the winter (3-month SST departure in the Nino-3.4 region cooler than -0.9°C).  In addition, a weaker second La Niña winter has occurred in three of the five multi-year La Niña’s in the historical SST record since 1950.  However, the NCEP Climate Forecast System (CFS.v1) predicts a moderate-strength La Niña this winter (3-month SST departure in the Nino-3.4 region between –1.0°C to –1.4°C) and CFS.v2 predicts a strong La Niña (3-month SST departure in the Nino-3.4 region cooler than –1.5°C), which rivals last year’s peak strength. For CFS forecasts made at this time of year, the average error for December-February is roughly ±0.5°C, so there is uncertainty as to whether the predicted  amplitude will be achieved. Thus, at this time, a weak or moderate strength La Niña is most likely during the Northern Hemisphere winter.

            Weekly updates of oceanic and atmospheric conditions are available on the Climate Prediction Center homepage (El Niño/La Niña Current Conditions and Expert Discussions).