The last mentioned advantage also implies that the community WRF-Var system should be enhanced by complementing the current 3D- to a 4-dimensional capability, using the WRF forecast model as a constraint, in order to provide the best initial conditions for the WRF model. The 4D-Var component of WRF-Var has been under extensive development since 2004. The prototype 4D-Var was built in 2005 and has under continuous refinement since then. Many single observation experiments have been carried out to validate the correctness of the 4D-Var formulation. A series of real data experiments have been conducted to assess the meteorological performance of the 4D-Var system. Preliminary results indicate that the 4D-Var works properly and can be used to assimilate many observations of different types.