Latest forecast of Nino3.4 index (slide 2) Hindcast skill of Nino3.4 index (slide 3)

1. Summary of CFS ENSO ForecastJuly 2010 updateMingyue Chen, Wanqiu Wang and Arun Kumar Climate Prediction Center Outline • Latest forecast of Nino3.4 index (slide 2) • Hindcast skill of Nino3.4 index (slide 3) • Hindcast scatter plots of Nino3.4 index (slide 4) • Verification of forecast for June 2010 and AMJ 2010 (slides 5-16)

2. Latest Nino3.4 SST forecast from July 2010 Forecasts from the latest initial conditions show that the current below-normal Nino3.4 SST will be enhanced in the next 5 months. The PDF corrected forecasts show smaller amplitude of ensemble means and smaller spreads among individual forecast members.

3. Hindcast skill of Nino3.4 index from July initial conditions Correlation RMSE (K) RMSE (K) PDF corrected PDF corrected PDF correction shows smaller (larger) RMSE during Aug-Oct & Feb-Apr(Nov-Jan). Correlation skills of PDF corrected are slightly lower.

4. Hindcasts of SONNino3.4 index from Julyinitial conditions Raw anomalies PDF corrected anomalies PDF correction does not show much improvement for SON forecast from July initial condition.

5. Verification of AMJ 2010 Nino34 SST forecast at different leads AMJ 2010 Nino3.4 forecast ensemble means are too warm from initial conditions of Nov 2009 to Jan 2010, and are close to observation from initial conditions of Feb-Mar 2010 (slide 6). Verification of CFS Forecast for June 2010 and AMJ 2010 Analysis of forecast for June 2010 from previous initial months Nino34 SST: Nino3.4 SST June 2010 forecasts did not catch the weak cold anomaly until from initial condition of Mar 2010. The forecast was too warm from initial condition before Mar 2010. No clear improvement with PDF correction at lead time beyond 2 months or so (slide 7&8). Spatial SSTs:The CFS over predicted the warmth in the tropical E. Pacific and SE Pacific but under predicted the warmth over the tropical Atlantic in the forecasts from Jan – Mar 2010. The warm bias over the tropical E. Pacific changes to cold bias from initial condition of Apr - May 2010 (slides 9-10). Taux and subsurface temperatures:Consistent with the errors in SST, the CFS produced large westerly errors in the western/central tropical Pacific in June 2010 forecasts from Jan – Mar 2010. Forecasts for June 2010 also showed warm errors in subsurface temperature east of the Date Line (slides 10-14). Impacts of intraseasonal variability:The westerly anomalies in late Jan and early Feb 2010 in the C. Pac. appeared to have led to the continued forecast of westerly anomalies in the E. Pac. Conversely, the strong easterly anomalies in the W. Pac around late Apr and early May 2010 may have contributed to the sustained easterlies and thus colder SSTs in the forecasts. Observed intraseasonal activities after May were weak(slide 6-10, 15-16).

6. 1-month Lead from Feb 4-month Lead from Nov 0-month Lead from Mar 3-month Lead from Dec 2-month Lead from Jan For AMJ2010 as the Target; Forecasts From Different Leads

16. Intraseasonally filtered anomaly with respect to initial time