The impact of probabilistic tornado warnings on risk perceptions and responses

Many warnings issued to members of the public are deterministic in that they do not include event likelihood information. This is true of the current polygon-based tornado warning used by the American National Weather Service, although the likelihood of a tornado varies within the boundaries of the polygon. To test whether adding likelihood information benefits end users, two experimental studies and one in-person interview study were conducted. The experimental studies compared five probabilistic formats, two with color and three with numeric probabilities alone, to the deterministic polygon. In both experiments, probabilistic formats led to better understanding of tornado likelihood and higher trust than the polygon alone, although color-coding led to several misunderstandings. When the polygon boundary was drawn at 10% chance, those using probabilistic formats made fewer correct shelter decisions at low probabilities and more correct shelter decisions at high probabilities compared to those using the deterministic warning, although overall decision quality, operationalized as expected value, did not differ. However, when the polygon boundary was drawn around 30%, participants with probabilistic forecasts had higher expected value. The interview study revealed that, although tornado-experienced individuals would not shelter at 10% chance, they would take intermediate actions, such as information-seeking and sharing. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Eyeing the storm: How residents of coastal Florida see hurricane forecasts and warnings

This paper examines the societal dimensions of warning decisions during extreme weather events in one of the most hurricane-prone areas in the U.S., Miami-Dade County, Florida. With the aim of informing improvements in the hurricane forecast and warning system, and better understanding warning decisions in extreme weather events, we explore how members of the public obtain and use hurricane forecasts and warnings in decision making. Results from in depth mental models interviews with members of the public (N=28) and survey data from three counties in Florida (N=460) show that a large majority of respondents have some hurricane experience, which influences their thinking about storm impacts, individual actions to mitigate the hazard, and vulnerability to the hazard. Comparison with results from previous research with warning system professionals (National Weather Service forecasters, media broadcasters, and public officials) indicates several gaps between professionals and laypeople including different perceptions of hurricane risks overall and related to flooding from storm surge. The findings suggest several areas for improvements in the hurricane forecast and warning system.

Learning to Expect Surprise: Hurricanes Harvey, Irma, Maria, and Beyond

Extreme events often bring unexpected situations and impacts, as the sequence of hurricanes and other natural disasters in summer and fall 2017 demonstrated. To reduce the risks associated with such events, many have focused on reducing uncertainty in prediction or reducing vulnerability. Although both are worthy goals, we suggest that the research community should also be focusing on the nature of surprise itself, to investigate the role of surprise in extreme events and its implications. Surprise arises when reality differs from people’s expectations. Multiple factors contribute to creating surprise, including the dynamic nature of natural and human systems, the limitations of scientific knowledge and prediction, and the ways that people interpret and manage risks, not to mention climate variability and change. We argue that surprise is an unavoidable component of weather and climate disasters — one that we must acknowledge, learn to anticipate, and incorporate into risk assessment and management efforts. In sum, although it may seem paradoxical, we should be learning how to expect surprise.