Atmospheric observational studies reveal synoptic-scale eastward-traveling modes, but barotropic models of the atmosphere do not have free Rossby modes in the discrete spectrum that travel eastward. Nevertheless, we show that eastward-traveling barotropic modes can be excited in the same way as discrete westward-traveling normal-mode Rossby waves. Within a linearized shallow water model, we have examined the response to forcing in individual hemispheres. This response includes eastward-traveling modes that agree well with observations. The study also shows resonant low-frequency responses in the continuous spectrum confined to a single hemisphere (hemispheric Rossby modes). ¿ 1999 American Geophysical Union