An emerging synoptic heat warning system that is based upon health outcomes rather than meteorological data alone has been applied to Madison and Milwaukee, Wisconsin, in a pilot study. This warning system aims to better prepare the cities to act and save lives during dangerous heat waves by better communicating their relative risks through different categories. We monitored this warning system in real time over summer 2022 and performed a retrospective analysis to see how its calls agreed or disagreed with calls from the National Weather Service and where the source of disagreement may be. In this talk, we discuss how this warning system was built, how well it performed this past summer, and how it can be improved and more widely used in the future.