Abstract
In mid-1966 a new baroclinic numerical weather prediction model became operational at the National Meteorological Center, an event made possible by advances in computer and communications technology. The new model integrates directly the primitive (hydrostatic) hydrodynamic and thermodynamic equations, a departure from previous operational models whose central dynamic equation was that of conservation of vorticity. In its first fourteen months of operational use, it has resulted in highly significant improvements in the Center's products.
