End user and forecaster interpretations of the European Avalanche Danger Scale: A study of avalanche probability judgments in Scotland

We investigate Scottish end users' and professional forecasters' risk perception in relation to the 5-point European Avalanche Danger Scale by eliciting numerical estimates of the probability of triggering an avalanche. Our main findings are that neither end users nor professional forecasters interpret the avalanche danger scale as intended, that is, in an exponential fashion. Second, we find that numerical interpretations by end users and professional forecasters have high variance, but are similar, in that both groups tend to overestimate the probability of triggering an avalanche and underestimate the relative risk increase. Finally, we find significant differences in the perceived probability of triggering an avalanche relative to a low or moderate avalanche danger level, and in the numerical interpretation of verbal probability terms depending on whether respondents provide their estimates using a frequency or a percentage chance format. We summarize our findings by identifying important lessons to improve avalanche risk understanding and its communication.