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Summary of CFS ENSO Forecast

April 2010 update

Mingyue Chen, Wanqiu Wang and Arun Kumar

Climate Prediction Center

1. Latest forecast of Nino3.4 index (slide 2)

2. Verification of forecast for March 2010 and JFM 2010 (slides 3-12)

Outline

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The forecasts from the latest initial conditions show that the Nino3.4 warm anomalies will be reduced to near normal or weak cold condition during next 5 months, then will be changed to cold conditions (after Oct 2010). The PDF corrected forecasts show smaller amplitude of ensemble means with smaller spreads.

Latest Nino3.4 SST forecast from April 2010

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Verification of CFS Forecast for Mar 2010 and JFM 2010

Nino34 SST: Nino3.4 SST Mar 2010 forecasts are too warm from initial conditions of Sep 2009-Jan 2010 and are close to observation from initial condition of Feb2010 (slide 5).

Spatial SSTs: Mar 2010 SST forecasts show warm errors over tropical E. Pacific and SE Pacific from the initial conditions from Oct 2009-Feb 2010. The magnitude of the warm errors in the forecast is reduced as the lead time getting shorter (slides 6-7).

Taux and subsurface temperatures: Mar 2010 forecasts from previous initial months (Sep2009-Feb2010) show westerly errors over tropical central Pacific and easterly errors over tropical E. Pacific. These surface wind errors are consistent with the warm errors in the SST and subsurface temperature. Mar 2010 forecast of subsurface temperature from initial condition of Jan 2010 shows large warm errors at E. Pacific that might be related to large westerly errors over central Pacific in Feb 2010 surface wind forecast (slides 6-11).

Impacts of intraseasonal variability: The easterly anomalies in late Dec 2009 over WPac may have contributed to the reduced warm amplitude of Nino3.4 SST forecast (slide 5 & 12). The impact of intraseasonal variability on the SST forecast in last several months is not clear.

Analysis of forecast for March 2010 from previous initial months

Observed JFM 2010 Nino3.4 SST is within the forecast range for forecasts from Aug to Dec 2009 and is slight colder than the forecast ensemble mean (slide 4).

Verification of JFM 2010 Nino34 SST forecast at different leads

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For JFM 2010 as the Target; Forecasts From Different Leads

4-month Lead

3-month Lead

2-month Lead

1-month Lead

0-month Lead

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