We consider the formation of slow shocks in a simplified model corona consisting of closed magnetic field lines near the coronal base with overlying open magnetic field lines. An increase in the magnetic field strength in the closed region is used to drive the corona outward, resulting in the generation of slow shocks for a suitable choice of parameters. The nature of the initial corona and the driver cause the field to be deflected around the expanding driver region and thereby produce a slow shock with a geometry that is concave upward (away from the Sun). The fastest-moving response generated in the corona occurs across nonlinear, fast-mode simple waves that are expansive over the driver region and compressive at the flanks. A nonlinear intermediate wave forms between the preceding fast wave and the following slow shock. This study not only demonstrates that concave-upward slow shocks can be formed in a magnetic environment, such as our simple model of the solar corona; it also provides the first evidence that nonlinear manifestations of all three wave modes may occur as the corona adjusts from ambient conditions to those produced by the driver. ¿ American Geophysical Union 1990