ESCAPE will support emerging extreme-scale markets by investigating specific models of heterogeneous architectures for one of the most challenging scientific applications. The specific complexity of NWP workflows, ingrained in the existing legacy applications, requires a new approach for the hybrid usage of conventional and low-energy processor types. Specific to NWP are the fundamentally large memory requirements, the combination of global and local stencil-type operations, and the very high FLOP rates needed for completing high-resolution complex sets of equations in prescribed wall-clock time limits with highest possible reliability. ESCAPE will produce a template for heterogeneous architectures applicable to a wide community in weather and climate forecasting. The involvement of industrial partners, namely Bull (and indirectly Cray), currently providing the bulk of the European HPC systems, indicates the significant economic interest of hardware vendors in defining new heterogeneous architecture templates. The involvement of a European SME (partner OSYS) investing in the emerging technology of optical processors is expected to produce fundamental insights and opens new market opportunities.