Tsunami Warning Systems describes the processes involved in anticipating, detecting, and warning for a tsunami by summarizing data collection, modeling, analysis, and alert procedures used at NOAA's Tsunami Warning Centers. A simulated event and past tsunami occurrences are used to highlight warning system processes for determining the tsunami threat based on seismic and sea level data and tsunami forecast models. Message communication and local response are also addressed as final components of any warning system. The module is intended for Weather Forecast Office staff and emergency managers who require a better understanding of the technical aspects of tsunami warning delivery. The module will also benefit anyone wanting to learn more about the components of tsunami warning systems.