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N.B.
This link is provided as a courtesy for
those interested in back country travel. The Ministry of
Forests cannot assume any responsiblity for its contents nor
its use for any particular purpose. We caution all potential
users that this type of information is quickly dated and has
limitations. All back country users are expected to use good
judgment when traveling in these areas.
 Canadian Avalanche Association
Forestry Avalanche Handbook
The Columbia Forest District contains some of the highest
avalanche prone areas in the province. It is hoped that this
manual will provide MOF staff with guidance and information that
will assist them in the performance of their duties.
This handbook is the first draft and is for discussion purposes
only.
Classification Systems
Several classification systems are used throughout the world in rating hazards and
conditions associated with avalanches. Those presented here are based on the Canadian
system.
Canadian Snowpack Stability Rating
| Stability Rating |
Description |
| Good Stability |
Natural avalanches are not expected. Skiers or explosives could trigger small
avalanches on very steep terrain (gullies, cliffs etc.) |
| Fair Stability |
Natural avalanches are not expected. Skiers could start avalanches on steep slopes.
Explosive charges are required to start avalanches on other slopes. |
| Poor Stability |
Natural avalanches can start with small triggers such as loading from blowing snow or
new snowfall or a rise in temperatue. Skiing and explosives will usually trigger
avalanches. |
| Very Poor Stability |
Natural avalanches run. Skiing and explosives will produce avalanches. |
Canadian rating for avalanche hazards to road traffic
| Hazard Rating |
Description |
| Low |
No avalanches are likely to run on the roadway. |
| Moderate |
The snow stability is poor. Avalanches affecting the road are expected to be small.
Powder avalanches could cross road. |
| High |
The snow stability is very poor. Avalanches hazardous to traffic are expected. |
| Extreme |
Numerous large avalanches are expected to affect the road. |
Canadian Snow Avalanche Size Classification System
| Size |
Description |
Typical Mass |
Typical Path Length |
Typical Impact Pressures |
| 1 |
Relatively harmless to people |
10 t |
10m |
1 kPa |
| 2 |
Could bury, injure or kill a person |
100 t |
100m |
10 kPa |
| 3 |
Could bury a car, destroy a small building or break a few trees |
1,000 t |
1,000m |
100 kPa |
| 4 |
Could destroy a railway car, large truck, several buildings or a forest with an area
up to 4 hectares |
10,000 t |
2,000m |
500 kPa |
| 5 |
Largest snow avalanches known; could destroy a village or a forest of 40 hectares |
100,000 t |
3,000m |
1,000 kPa |
1 hectare = 2.471 acres
The Ministry of Forests does not endorse specific materials relating to avalanches.
However, those interested in a mildly technical treatment of the subject may find the
following publication of interest. Much of the source material for this publication was
drawn from research conducted in the Selkirk mountains found within the Columbia Forest
District.
The Avalanche Handbook by David McClung & Peter Schaerer (ISBN
0-89886-364-3), published by the
The Mountaineers
1001 SW Klickitat Way
Seattle WA 98134
1-800-553-4453
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