1. A control system for controlling a process using a parametric model-based control technique, comprising: an input through which a set point for the process is input; an output through which a control output is output to the process for controlling the process; and a controller in which a behavior of the process is represented with a model, the model based on at least one time-varying parameter, and the controller configured to: establish a model output array that contains output values of the model for a series of time samples that includes a time sample corresponding to an estimated dead time of the process; revise at least a portion of the model output array that corresponds to time samples occurring after the dead time of the process, the revision based on a change in the time-varying parameter; establish a disturbance array that contains disturbance values for the process for the series of time samples; revise at least a portion of the disturbance array that corresponds to the revised portion of the model output array so that, for each revised time sample, a predicted process value determined after the change in time-varying parameter is the same as a predicted process value determined before the change; and generate a bumpless transfer as the control output for the set point based on the revised model output array and the revised disturbance array in response to the change in time-varying parameter.