Communicating increased risk: An empirical investigation of the National Weather Service's impact-based warnings

In 2014, following a Central Region pilot assessment, the National Weather Service implemented largescale use of an experimental product of enhanced severe weather warnings known as impact-based warnings (IBWs). The overarching goal of these IBWs is to improve the threat warning process and motivate appropriate responses by using event tags and additional text that provides more specificity about the magnitude of the storm and its potential consequences. These IBWs are designed to be used by individuals in the field to make more effective decisions. Although qualitative research has shown overall satisfaction with IBWs (Harrison et al. 2014; Losego et al. 2013), little published experimental research has been conducted on these new enhanced warnings. The research reported here therefore empirically investigates the effectiveness of the new IBW experimental product. In three experiments, participants adopted the role of a plant manager and read both IBWs and non-IBWs. At three different decision points, participants made decisions about shutting down the plant and having employees shelter in place. The results of all three experiments show that the IBWs produced higher likelihoods of closing the plant and sheltering in place, but only after the additional IBW text (providing information about the hazard, source, and impact) was presented. Interestingly, participant background knowledge of tornadoes and severe weather had little impact on their shelter in place decisions. The results support the conclusion that the additional enhanced text in IBWs promotes a higher stated likelihood of sheltering in place, at least as measured by behavioral intentions.