Working Group on International classification of snow avalanches (2026-2029)

WG proposal

WG co-chairs

J.-T. Fischer, Austrian Research Centre for Forests, Innsbruck, Austria
Scott Thumlert, Alpine Solutions, Canmore, AB, Canada

Collaborators

Erich Peitzsch, Northern Rocky Mountain Science Center, West Glacier, MT, USA
Ethan Greene, Colorado Avalanche Information Center, USA
Satoru Yamaguchi, National Research Institute for Earth Science and Disaster Resilience, Nagaoka, Japan
Cesar Vera, Wyssen Avalanche Control, Reichenbach, Switzerland
Thomas Feistl, Bavarian Avalanche Warning Service, Munich, Germany
Momchil Panayotov, University of Forestry, Sofia, Bulgaria

Motivation

The Avalanche Atlas – Illustrated International Avalanche Classification (De Quervain et al., UNESCO, 1981) was a landmark achievement in snow and avalanche science. It provided a unified, multilingual framework for describing avalanches in terms of genetics and morphology. For more than four decades it has served as a trusted reference for researchers, practitioners, and educators in hazard management worldwide. Since its publication, avalanche science has advanced dramatically. Field experiments and laboratory observations, modeling and simulation or operational forecasting and hazard mapping have deepened our understanding of avalanche formation, dynamics, and impacts. Modern documentation tools —from high-resolution photogrammetry to satellite and lidar surveys – enable more precise, consistent, and globally applicable descriptions than were possible in 1981.

From 2019 to now the idea of a formal, well-organized working group on an updated avalanche classification scheme sparked within the international avalanche community. In April 2025, the parts of the international avalanche community met in Fonnbue, Norway, to discuss the current state of avalanche dynamics, reaching the conclusion to establish a formal working group to renew the Avalanche Atlas. The group agreed that the updated framework should:
• better represent the relationship between avalanche size and flow regime;
• revise morphological classification to reflect current science and operational needs;
• expand genetic classification with recent insights into release mechanisms and in conjunction with operational communication schemes in avalanche warning;
• improve the integration of path-related and event-related descriptors in avalanche documentation, particularly in relation to the relevant snow climate.

While the scientific goal is to advance avalanche analysis and classification, the practical goal is to improve quantity and quality of the global exchange of avalanche information. A modernized, harmonized International Classification of Avalanches will allow practitioners worldwide to work with a coherent, scientifically robust, and widely accepted system, strengthening safety, research quality, and cross-border cooperation in mountain regions globally.

Objectives

The renewed Avalanche Atlas will build on the 1981 edition by systematically reviewing the original classification alongside national and regional adaptations to identify overlaps, inconsistencies, and gaps. The resulting harmonized framework will preserve the historical foundation while integrating four decades of scientific and operational advances.

Key objectives include:
• Updating avalanche size classification to integrate operational standards (such as relative and absolute size schemes) and modern measurement capabilities.
• Refining morphological classification through clearer terminology, improved visual documentation, and inclusion of transitional flow regimes.
• Expanding genetic classification to incorporate distinctions related to the prevailing topographic or snow climate conditions.
• Developing a dual-structured system that distinguishes permanent path-related attributes from event-specific characteristics, enabling consistent, comparable avalanche documentation worldwide.
• Forward–backward compatibility to ensure the smooth transition of existing systems into the updated classification and allowing/identifying potential for future developments. At the same time the framework should be compatible with current internationally harmonized and national standards (observation guidelines, avalanche hazard, avalanche problems, international classification of snow on the ground).

A central scientific aim is to develop a more sophisticated representation of how avalanche size relates to the governing flow regimes, clarifying links between avalanche properties, such as volume, impact pressure, runout distance and critical flow characteristics density, temperature or liquid water content.

The revised classification will be designed for interoperability with avalanche warning, and research databases, ensuring global applicability. It will be developed through international collaboration, supported by open-access documentation and training resources, and optimized for hazard management, communication, and long-term risk assessment; at the same time, it will provide the basis for scientific discourse and highlight existing knowledge gaps.

Tasks and Activities

Task 1: Review and harmonize existing avalanche classification systems
Consolidate the 1981 Avalanche Atlas with later national and regional schemes, identifying inconsistencies and integrating modern scientific advances. The international avalanche community will provide national classification documents, operational guidelines, and expert input to ensure a globally representative standard.

Task 2: Modernize avalanche size, morphological, and genetic classifications
Update definitions, align them with operational standards, and integrate advances in snow science and measurement technology. This includes refining the link between size and flow regime, and improving genetic classification by connecting it to potentially recognized avalanche problem types. Expert workshops, held alongside the ISSW or other conferences and workshops, will facilitate consensus on definitions, boundaries, and operational links.

Task 3: Define snow and avalanche climates
Establish clear, consistent, and internationally accepted definitions to improve scientific comparability and operational communication. A specialized sub-working group—comprising climatologists, avalanche forecasters, and researchers—will lead this work, drawing on regional climate data, long-term avalanche records, and case studies from across the globe.

Task 4: Integrate path-related and event-related features into a dual-structured avalanche documentation framework
Implement a system where permanent terrain/environmental attributes (path-related) and individual occurrence characteristics (event-related) are recorded independently but linked. This will be supported by a standardized avalanche recording sheet (avalanche profiler), developed in cooperation with avalanche associations and national/regional warning services. Targeted workshops will define mandatory parameters, measurement methods, and sheet structure to ensure global consistency.

Deliverables

The primary outcome will be the publication of the Renewed Avalanche Atlas – International Avalanche Classification, presenting a harmonized, multilingual framework that integrates modern scientific knowledge, operational experience, and standardized terminology. This atlas will serve as a global reference for hazard zoning, event documentation, and risk assessment, adaptable to mountain environments worldwide.