The Influence of Consequence-Based Messages on Public Responses to Tornado Warnings

Abstract

The Central Region Headquarters of the National Weather Service (NWS) recently launched an experimental product that supplements traditional tornado and severe thunderstorm warning products with information about the potential impact of warned storms. As yet, however, we know relatively little about the influence of consequence-based messages on warning responsiveness. To address this gap, we fielded two surveys of U.S. residents that live in tornado-prone regions of the country. Both surveys contained an experiment wherein participants were randomly assigned a consequence-based tornado warning message and asked to indicate how they would respond if they were to receive such a warning. Respondents that were assigned to higher-impact categories were more likely choose protective action than respondents assigned to lower-impact categories. There was, however, a threshold beyond which escalating the projected consequences of the storm no longer increased the probability of protective action. To account for this, we show that the relationship between consequence-based messages and protective action depends on the type of action being considered. At lower levels of projected impact, increasing the expected consequences of the storm simultaneously increased the probability that respondents selected a “shelter in place” or “leave residence” option. At higher levels of projected impact, this relationship changed—increasing the projected consequences of the storm decreased the probability that respondents would shelter in place and increased the probability that they would leave their residence for what they perceived to be a safer location. In some severe storm situations, this behavior may increase rather than decrease the risks.

Throwing Caution to the Wind: National Weather Service Wind Products as Perceived by a Weather-Salient Sample

“…Although the impact from nonconvective winds can vary substantially from a convective event (e.g., a tornado), perhaps similarities can be drawn between the two hazards. Ripberger et al (2015) discovered that survey participants in tornado-prone areas were more likely to take protective action when impact-based information was included in the warning text for convective hazards. Our results from section 3b suggest that individuals may exhibit similar tendencies because of the number of respondents who defined these wind products using impact-related information.…”

“…Our results from section 3b suggest that individuals may exhibit similar tendencies because of the number of respondents who defined these wind products using impact-related information. However, Ripberger et al (2015) also noted that the use of impact-based information was only successful to a certain degree. The authors explained that increasing the intensity of stormrelated impact information "prompt [ed] decreases in the probability that respondents would shelter in place and increases in the probability that respondents would leave their residences for a safer location."…”

A skill assessment of techniques for real-time diagnosis and short-term prediction of tornado intensity using the WSR-88D

“…For example, V rot values >28.29 m s -1 (55 kt) are likely to be associated with a strong tornado. The chart also reflects the frequent overlapping of values between ranges (Kingfield and LaDue 2015; Smith et al 2015). For instance, V rot values of 20.57-28.29 m s -1 (40-55 kt) lie within the overlap between weak and strong tornadoes.…”

“…Warning tags can be modified following the initial issuance to upgrade or downgrade the language used [Warning Decision Training Division (WDTD) 2016a]. Ripberger et al (2015) examined the results of the consequence-based messaging used in IBW, and found that it would tend to make individuals in the path of a tornado more likely to take the proper protective action. The likelihood of proper protective action reached a point of diminishing returns when the strongest language was used, leading to a small decrease in protective action rate.…”

“…However, overall skill scores were as high as the skill in differentiating between tornadic and nontornadic signatures. Smith et al (2015) produced probabilities of the report of a given EF-scale damage based on (i) observed V rot values and (ii) environmental conditions evaluated with the significant tornado parameter . The study showed skill at discriminating tornado intensity.…”