Advances in the Lead Time of Sahel Rainfall Prediction With the North American Multimodel Ensemble

Abstract : We assess the deterministic skill in seasonal climate predictions of Sahel rainfall made with the North American Multimodel Ensemble (NMME). We find that skill for a regionally averaged rainfall index is essentially the same for forecasts for the July–September target season made as early as February/March and as late as June. The two dominant influences on the climate of the Sahel, the North Atlantic and the global tropical oceans, shape this predictability. Multimodel ensemble skill hinges on the combination of skillful predictions of the El Niño–Southern Oscillation made with one model (CMC2‐CanCM4) with those of North Atlantic sea surface temperatures made with another (NASA‐GEOSS2S).