Hot Pockets: Rethinking the National Weather Service Approach to Heat Hazards in the Louisville Urban Heat Island

Heat kills more Americans annually than any other type of weather hazard. Compared to other populations, Americans in cities may be at greater risk due to the amplification of ambient heat by urban heat islands. In Louisville, people are exposed to what has been identified as one of the strongest and fastest growing urban heat islands in the country. To aid National Weather Service (NWS) operations, this study investigates the relationship between heat illness and weather conditions in the Louisville metropolitan area. For each zip code in Louisville, dates corresponding to an elevated number of heat-related EMS calls were identified. The weather on these elevated dates were compared for urban and non-urban zip codes using the Mann Whitney U test. Overall, a number of challenges were encountered, including noncontinuity of EMS records and privacy limitations on medical data.

Preliminary results suggest that the weather underlying elevated heat incidents are significantly different between urban and non-urban zip codes. However, considerable overlap remains between urban and non-urban distributions. This precludes the use of a single threshold to identify conditions dangerous for people inside, but not outside, the urban heat island. As data limitations may be obscuring trends, future work seeks to refine existing data and to use additional sources, such as hospitalization records. Further steps also include additional statistical analyses, as well as the development of a heat warning index that incorporates multiple variables. In the meantime, relationships established between NWS Louisville and public health officials support a collaborative effort to create a Weather-Ready Nation.