Log Cabin Mountain ATES
|Simple||1||Exposure to low angle or primarily forested terrain. Some forest openings may involve the runout zones of infrequent avalanches. Many options to reduce or eliminate exposure. No glacier travel.|
|Challenging||2||Exposure to well defined avalanche paths, starting zones or terrain traps; options exist to reduce or eliminate exposure with careful routefinding. Glacier travel is straightforward but crevasse hazards may exist.|
|Complex||3||Exposure to multiple overlapping avalanche paths or large expanses of steep, open terrain; multiple avalanche starting zones and terrain traps below; minimal options to reduce exposure. Complicated glacier travel with extensive crevasse bands or icefalls.|
The technical model has been designed for users trained and skilled in the subtle nuances of avalanche terrain.
|1 - Simple>||2 - Challenging||3 - Complex|
|Slope angle||Angles generally < 30º||Mostly low angle, isolated slopes >35º|| Variable with large % >35º
|Slope shape||Uniform||Some convexities||Convoluted|
|Forest density||Primarily treed with some forest openings||Mixed trees and open terrain||Large expanses of open terrain. Isolated tree bands|
|Terrain traps||Minimal, some creek slopes or cutbanks||Some depressions, gullies and/or overhead avalanche terrain||Many depressions, gullies, cliffs, hidden slopes above gullies, cornices
|1:30 ≥ size 2||1:1 for < size 2
1:3 for ≥ size 2
|1:1 < size 3
1:1 ≥ size 3
|Start zone density||Limited open terrain||Some open terrain. Isolated avalanche paths leading to valley bottom||Large expanses of open terrain. Multiple avalanche paths leading to valley bottom
|Runout zone characteristics||Solitary, well defined areas, smooth transitions, spread deposits||Abrupt transitions or depressions with deep deposits||Multiple converging runout zones, confined deposition area, steep tracks overhead
|Interaction with avalanche paths||Runout zones only||Single path or paths with separation||Numerous and overlapping paths
|Route options||Numerous, terrain allows multiple choices||A selection of choices of varying exposure, options to avoid avalanche paths||Limited chances to reduce exposure, avoidance not possible
|Exposure time||None, or limited exposure crossing runouts only||Isolated exposure to start zones and tracks||Frequent exposure to start zones and tracks
|Glaciation||None||Generally smooth with isolated bands of crevasses||Broken or steep sections of crevasses, icefalls or serac exposure
Using this scale
Any given piece of mountain terrain may have elements that will fit into multiple classes. Applying a terrain exposure rating involves considering all of the variables described above, with some default priorities:
- Terrain that qualifies under an italicized descriptor automatically defaults into that or a higher terrain class.
- Non-italicized descriptors carry less weight and will not trigger a default, but must be considered in combination with the other factors.