Lives Saved versus Time Lost: Direct Societal Benefits of Probabilistic Tornado Warnings

Abstract

Abstract The National Weather Service is planning to implement the system of probabilistic tornado warnings. In this paper, I estimate and compare the full societal costs of tornadoes with existing deterministic and potential probabilistic warnings. These full costs include the value of statistical lives lost as well as the value of the time spent sheltering. I find that probabilistic tornado warnings would decrease total expected fatalities. The improvement in decision-making would also decrease the total opportunity cost of time spent sheltering, even though the total sheltering time is likely to increase. In total, probabilistic warnings should lower the societal costs of tornadoes relative to deterministic warnings by approximately $76–139 million per year, with a large portion of this improvement coming from fewer casualties. Significance Statement I measure societal benefits of probabilistic and deterministic tornado warnings in the United States by evaluating their effects on expected casualties and sheltering costs. I find that probabilistic warnings deliver almost twice as much net societal benefit as deterministic ones. These gains happen as a result of fewer casualties and making protective behavior more responsive to risks and sheltering costs. This paper provides additional evidence of the need to implement probabilistic extreme weather warnings.