A high-resolution radar data assimilation system is under development at the Naval Research Laboratory for the Navy's Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS™). The data assimilation system uses a variational approach, together with other data fusion technologies, to retrieve three-dimensional cloud and wind fields from radar observations of radial velocity and reflectivity from multiple radars inside an analysis domain. This system also uses satellite data and surface observations for retrieving cloud and precipitation information. The products from this system are used to initialize the high-resolution COAMPS model, and at the same time, to provide detailed dynamical and hydrological structures of the three-dimensional atmosphere for the NOWCAST program at the Naval Research Laboratory. The high-resolution winds from the data assimilation system as well as from the COAMPS™ model forecast will be used to drive chemical/biological (CB) dispersion models (Hazard Prediction and Assessment Capability (HPAC) and Vapor, Liquid, and Solid Tracking (VLSTRACK)) for CB defense. Extensive testing of the system has been conducted with NEXRAD level-II data and the Navy's SPY-1/TEP shipboard radar data. The results from the tests have showed positive impact of radar observations on wind and cloud analyses.