Peta or Exa scale computers requires codes with a high scalability. Classical Numerical Weather Prediction (NWP) codes like WRF have a lack of scalability. To produce new NWP codes with high scalability we need the techniques developed by the Computational Fluid Dynamics (CFD) community. It is difficult for a newcomer in the NWP community to find similarities with CFD techniques as far as the numerical methods of the dynamical cores in NWP are concerned.

Different variables than the CFD traditional conservative one are used and seemingly different discretization techniques have been developed, whereas the same Euler equations are being solved in both cases. So the first aim is to compare and contrast the main numerical elements used in both communities. The second aim consists in validating a CFD solver adapted to NWP to a set of traditional NWP benchmarks. It is shown that it produces accurate and low diffusive results. The obvious advantage of this approach is that it allows in almost one solver to cover the NWP and CFD ranges of applications. Furthermore, the solver has been designed to run on fully three dimensional unstructured grids for geometric flexibility and adaptivity.