The Fundamental Processes in Conventional Alavalanche Forecasting

Abstract

ABSTRACT. Conventional avalanche forecasting is practiced as a mix of deterministic treatment for snow and weather parameters and inductive logic to reach actual forecast decisions. Inductive logic of the scientific method dominates, making frequent use of iteration and redundancy to minimize decision uncertainties. The mental processes involved are holistic rather than analytical. Elementary information theory can be used rationally to sort data categories for minimum entropy and optimize inductive reasoning. Recognizing these principles affords a chance to improve the practice and teaching of conventional forecasting techniques. RESUME. Les processus fondamentaux de la prevision conventionnelle des avalanches. La pn!vision conventionnelle des avalanches est pratiquee comme un melange d'un traitement deterministe des parametres relatifs a la neige et a la meteorologie et d'une logique inductive pour aboutir aux decisions reelles du previsionniste.La logique inductive de la methode scientifique domine, faisant un usage frequent de l'iteration et de la redondance pour diminuer les incertitudes de la decision. Les processus mentaux mis en oeuvre sont globaux plus qu'analytiques. On peut utiliser rationnellement une theorie elementaire de l'information pour choisir des categories de donnee d'enthropie minimum et optimiser le raisonnement inductif. La reconnaissance de ces principes apporte une chance d'ameliorer la pratique et l'enseignement des techniques conventionnelles de prevision.

A conceptual model of avalanche hazard

“…Avalanche forecasters strive to minimize this uncertainty by assimilating data and evidence accumulated incrementally over time (LaChapelle 1980), and extrapolating this across the landscape using their knowledge of local geography.…”

“…Even though avalanche forecasters have high levels of skill developed through empirical experience, they are often unable to communicate their methods, or their personal connection between experience and skill (LaChapelle 1980). To overcome this challenge, we used judgmental decomposition (MacGregor 2001;Vick 2002) to systematically break down avalanche hazard into a progressive series of subset components.…”

“…Uncertainty is inherent in all avalanche hazard and risk assessments; it can be reduced, but never eliminated (LaChapelle 1980;Jamieson et al 2015). Uncertainty creates doubt, and doubt (or lack of it) manifests itself in people and their actions.…”

Numerical avalanche prediction: Kootenay Pass, British Columbia, Canada

“…The basis for modern avalanche forecasting may be derived from the work of LaChapelle (1980). LaChapelle rationalized avalanche forecasting on the basis of three data classes and his work was extended by McClung and Schaerer (1993).…”

“…Application of Bayesian statistics allows a forecaster to input his/her a priori probability of avalanching based on empirical data which potentially allows use of non-numerical data from classes outside those used in numerical prediction to improve the prediction. This approach can synthesize numerical and conventional avalanche forecasting (see LaChapelle, 1980) and it can forge the link for the future development of a coupled expert system using empirical and numerical data from all three classes.…”