Tornado Warning Trade-Offs: Evaluating Choices for Visually Communicating Risk

Authors: Kevin D. Ash et al.

Discipline: Geography

Hazard of Interest: Tornado

Methods: Questionnaire, Mann-Whitney U test, Getis-Ord G*i Hotspot analysis, linear-by-linear chi-square test, GIS

Key Research Issues: Do deterministic-style and probabilistic-style tornado warning graphics elicit different fear responses and protective action intentions?

Key Findings:

• The deterministic warning showed higher fear and protective action responses than the probabilistic-style warnings

• Participant responses dropped off more sharply near the edge of the deterministic warning

• Probabilistic warnings elicited clusters of high fear and protective action responses coincident with the higher probabilities of a tornado, which aided in understanding the direction of movement implied by the warning shape and color patterns

• The cluster of high responses for the deterministic warning was near its centroid and did not clearly indicate that viewers understood the direction of movement from the shape alone