1. 1 Summary of CFS ENSO Forecast December 2010 update Mingyue Chen, Wanqiu Wang and Arun Kumar Climate Prediction Center 1.Latest forecast of Nino3.4 index (slide 2) 2.Hindcast skill of Nino3.4 index (slide 3) 3.Hindcast scatter plots of Nino3.4 index (slide 4) 4.Verification of forecast for November 2010 (slides 5-15) Outline

2. 2 CFS forecasts from the latest initial conditions show that the current cold Nino3.4 SST condition will continue in next 3 seasons. The PDF corrected forecasts show smaller amplitude of ensemble means and smaller spreads among individual forecast members. Latest Nino3.4 SST forecast from December 2010 CFSv2 predicts weaker La Nina state than CFS CFSv2 is comparable to CFS PDF corrected through Apr 2011, but weaker thereafter.

3. 3 PDF corrected RMSE (K) Hindcast skill of Nino3.4 index from December initial conditions PDF correction shows much smaller of RMSE during Feb-Jun than the un-corrected forecast. Correlation skills of PDF corrected are slightly lower than the un-corrected forecast. Correlation PDF corrected

4. 4 Hindcasts of FMA Nino3.4 index from December initial conditions Raw anomaliesPDF corrected anomalies PDF correction shows improvement for FMA forecast at cold anomalies from December initial condition.

5. 5 Verification of CFS Forecast for November 2010 Nino34 SST: Nino3.4 SST Nov 2010 forecasts show that the anomalies are colder than the observation from initial conditions June-Oct 2010. The PDF corrected forecasts show smaller cold amplitudes of ensemble means and much less spread among individual members. The Nov 2010 ensemble means of the PDF corrected forecast are closer to the observation than that of the raw forecasts (slide 6&7). Spatial SSTs: Anomalies in the tropical central Pacific and far E. Pacific to the South American coast are too warm, but those over tropical around 120W and the tropical Atlantic are too cold in the forecasts from initial conditions after June 2010(slides 8-9). Taux and subsurface temperatures: Consistent with the errors in SST, the CFS produced westerly errors in the central tropical Pacific and easterly errors in the E. Pacific in the forecasts from initial condition after June 2010. Forecasts for Nov 2010 subsurface temperature also show cold errors in east of the Date Line and warm errors in the far E. Pacific to the S. American coast (slides 10-13). Impacts of intraseasonal variability: Observed equatorial total 850mb zonal wind anomalies show intraseasonal variations together with more persisting easterly anomalies in the western Pacific after June 2010 (slide 14, left panel). Nino3.4 SSTs in the forecasts are below normal anomalies after June initial conditions (slide 14, right panel). The fluctuation of the forecast Nino3.4 SSTs appears to be related to the intraseasonal (10-70-day) wind variations in the western Pacific (slide 15). The strong easterly anomalies in the W. Pac around mid July, late Sep to early Oct, and early Dec may have contributed to the sustained easterlies and thus colder SSTs in the forecasts. The strong westerly around mid Oct 2010 may have contributed to the warmer SSTs in the forecast (slide 6-11, 14-15). Analysis of forecast for Nov 2010 from previous initial months

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15. 15 Intraseasonally filtered anomaly with respect to initial time