Potential predictability of tropical Indian Ocean SST anomalies

[1] Retrospective 9-month 15-member ensemble forecasts from the National Centers for Environmental Prediction Coupled Forecast System (NCEP CFS) for 1981 to 2003 are used to assess forecast skill and potential predictability of sea-surface temperature anomalies (SSTAs) over the poles of the Indian Ocean Dipole Mode (IDM). The CFS successfully forecasts through the boreal winter persistence barrier at the east IDM pole capturing the sign change of the SSTAs. Forecasts are skillful up to 3–4 months lead for first half-year starts, and into the following boreal spring for second half-year starts. West IDM pole forecasts are skillful up to 6–7 months lead or until mid-summer; skill returns in fall for forecasts initiated in boreal summer. Potential predictability of boreal fall SSTAs at lead times of 2–3 seasons appears limited by the onset of the boreal summer monsoon at both IDM poles with weak SSTAs, weak ocean-atmosphere coupling, and lack of good initialization of the subsurface ocean further hampering forecasts initiated in boreal winter at the east IDM pole.