Stability rating definition table
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Definition
Stability refers to the chance that avalanche will not initiate. Stability is analysed in space and time relative to sensitivity to triggers and spatial distributions. Stability evaluation does not consider the size or potential consequences of expected avalanches; avalanche hazard and risk evaluation includes consideration of these factors.
Snow stability rating system
| Stability rating | Sensitivity to triggers | Stability test results | ||
| Natural avalanches | Triggered avalanches | Test scores | Fracture character | |
| Very Good (VG) | No natural avalanches expected. | Avalanche may be triggered by very heavy loads, such as large cornice falls, in isolated terrain features. | Generally no results. | No fracture or non-planar break fractures. |
| Good (G) | No natural avalanches expected. | Avalanches may be triggered by heavy loads in areas in isolated terrain features. | Generally moderate to hard results. | Generally resistant or non-planar break fractures. |
| Fair (F) | Isolated natural avalanches are expected on specific terrain features. | Avalanche may be triggered by light loads in areas with specific terrain features or certain snowpack characteristics. | Generally easy to moderate results. | Resistant or sudden fractures |
| Poor (P) | Natural avalanches are expected in areas with specific terrain features or certain snowpack characteristics. | Avalanches may be triggered by light loads in many areas with sufficiently steep slopes. | Generally easy results. | Generally sudden fractures |
| Very Poor (VP) | Widespread natural avalanche expected. | Widespread triggering of avalanche by light loads. | Very easy to easy results. | Sudden fractures. |
Note:
- Statements about avalanche activity take precedence over results of stability tests.
- For regional and larger forecast areas isolated natural avalanches may occur even when the stability for the area as a whole is good.
Source:
Canadian Avalanche Association. (2007). Observation Guidelines and Recording Standards for Weather, Snowpack, and Avalanches. Revelstoke, BC.
