Linear instabilities have been found for tropospheric flows consisting of a mean zonal component and a tilted, forced, stationary wave. The eigensolutions of maximum growth rate provide an adequate explanation of the location and structure of regions of maximum bandpass transient activity (storm tracks). The study also highlights the importance of adequate resolution in models involving first-order coupling mechanisms, such as a standing wave. It identifies the curvature of the mean state as a possibly significant factor in determining the “baroclinicity” of a region.