Based on the COSMO-REA6 reanalysis system, a regional ensemble reanalysis COSMO-ENS-REA12 has been developed. The regional reanalysis system for Continental Europe has a coarser spatial resolution (12 km) than the deterministic COSMO-REA6 and matches the domain of the CORDEX EURO-11 specifications. It comprises the assimilation of observational data using a newly developed ensemble nudging scheme complemented by snow, SST and soil moisture analysis modules. Through this new approach it is possible to use deterministic lateral boundary conditions, that is, ERA‐Interim reanalysis data. The reanalysis data set currently covers a 5-year period 2006-2010.