Extended-range prediction

The production of extended-range forecasts is now a consolidated operational activity at ECMWF. It bridges the medium and the seasonal range from the perspective of users, model development and initialization options. This paper reviews five years of progress in the ECMWF forecasts at this time range and provides a summary of main lessons learns from the scientific exploitation of the S2S data base. A proposal for the extended-range forecasting system on the new HPC is presented. Developments for a longer time frame are described. They are being explored in the context of the second phase of the WWRP/WCRP sub-seasonal to seasonal (S2S) prediction project, which provides an opportunity to coordinate this research with the international community through coordinated experiments and analysis of the S2S database.