Avalanche Terrain Exposure Scale
Winter
Print friendly version (PDF, 56 KB)
The Avalanche Terrain Exposure Scale (ATES) is a new development from Parks Canada, which offers an avalanche classification system based on the landscape – not the snow. The system presents two models: technical, and public communication.
The technical model has been designed for users trained and skilled in the subtle nuances of avalanche terrain. The public communication model is designed for communicating technical concepts to the public, who is largely unable to comprehend the technical details. Both scales represent the same thing – spoken in two languages.
The ATES can be applied at whatever scale is appropriate. Parks Canada has chosen to link with popular guidebooks, and apply ATES ratings to backcountry trips, which are well described in these books. This classification could however, be applied to any given piece of terrain – it is all a question of scale.
Avalanche Terrain Exposure Scale defined
| 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 |
| Avalanche frequency (events:years) |
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.
Mount Revelstoke and Glacier terrain
| Name | Park | Class |
|---|---|---|
| 2km & 5km Loop trails | Mount Revelstoke National Park | Simple - Class 1 |
| 3 Pass Traverse | Glacier National Park | Complex - Class 3 |
| 8812 Bowl | Glacier National Park | Complex - Class 3 |
| Asulkan Hut/Tree Triangle | Glacier National Park | Complex - Class 3 |
| Asulkan Pass | Glacier National Park | Complex - Class 3 |
| Asulkan Valley Practice Slopes | Glacier National Park | Complex - Class 3 |
| Avalanche Crest - to treeline | Glacier National Park | Challenging - Class 2 |
| Avalanche Crest bowl/slidepath | Glacier National Park | Complex - Class 3 |
| Balsam Lake to Eva & Miller Lakes | Mount Revelstoke National Park | Challenging - Class 2 |
| Balsam Lake to Mt Revelstoke Summit | Mount Revelstoke National Park | Challenging - Class 2 |
| Balu Pass | Glacier National Park | Complex - Class 3 |
| Beaver River | Glacier National Park | Simple - Class 1 |
| Bonney Glacier | Glacier National Park | Complex - Class 3 |
| Bruins Pass | Glacier National Park | Complex - Class 3 |
| Cheops Glades | Glacier National Park | Challenging - Class 2 |
| Clachnacudain Creek | Mount Revelstoke National Park | Complex - Class 3 |
| Clachnacudain Creek east fork | Mount Revelstoke National Park | Complex - Class 3 |
| Clachnacudain Glacier-Inverness Peaks | Mount Revelstoke National Park | Complex - Class 3 |
| Cougar Valley | Glacier National Park | Complex - Class 3 |
| Coursier Creek | Mount Revelstoke National Park | Complex - Class 3 |
| Dome Glacier | Glacier National Park | Complex - Class 3 |
| Flat Creek slidepaths | Glacier National Park | Complex - Class 3 |
| Flat Creek valley trail | Glacier National Park | Challenging - Class 2 |
| Fortitude | Glacier National Park | Complex - Class 3 |
| Glacier Circle | Glacier National Park | Complex - Class 3 |
| Grizzly Shoulder | Glacier National Park | Challenging - Class 2 |
| Grizzly/Little Sifton Traverse | Glacier National Park | Complex - Class 3 |
| Hamilton Creek Upper Meadows | Mount Revelstoke National Park | Complex - Class 3 |
| Hermit Meadows | Glacier National Park | Challenging - Class 2 |
| Illecillewaet Neve access | Glacier National Park | Complex - Class 3 |
| Illecillewaet Practice Slopes | Glacier National Park | Complex - Class 3 |
| Inspiration Woods | Mount Revelstoke National Park | Simple - Class 1 |
| Lily Glacier | Glacier National Park | Complex - Class 3 |
| Lindmark Trail above Parkway Intersection | Mount Revelstoke National Park | Challenging - Class 2 |
| Lindmark trail to Parkway Intersection | Mount Revelstoke National Park | Simple - Class 1 |
| Lizards Tail | Glacier National Park | Complex - Class 3 |
| Lookout Col | Glacier National Park | Complex - Class 3 |
| Maunder Creek | Mount Revelstoke National Park | Complex - Class 3 |
| McGill Bowl - McGill Pass | Glacier National Park | Complex - Class 3 |
| McGill Shoulder | Glacier National Park | Challenging - Class 2 |
| Meadows in the Sky Parkway Summit Trail to 8 Mile Crossing | Mount Revelstoke National Park | Simple - Class 1 |
| Mount Klotz above treeline | Mount Revelstoke National Park | Complex - Class 3 |
| Mt. Rogers | Glacier National Park | Complex - Class 3 |
| Mt. Swanzy | Glacier National Park | Complex - Class 3 |
| Mt. Tupper Traverse | Glacier National Park | Complex - Class 3 |
| NRC Gullies | Glacier National Park | Complex - Class 3 |
| Perley Rock | Glacier National Park | Complex - Class 3 |
| Rogers Pass Ski Hill (forest cuts behind hotel) | Glacier National Park | Simple - Class 1 |
| Saint Syr Creek | Mount Revelstoke National Park | Complex - Class 3 |
| Sapphire Col | Glacier National Park | Complex - Class 3 |
| Sifton Col | Glacier National Park | Challenging - Class 2 |
| Smart Ridge | Glacier National Park | Complex - Class 3 |
| Steps of Paradise - Youngs Pk | Glacier National Park | Complex - Class 3 |
| Summit Trail above 8 Mile Crossing | Mount Revelstoke National Park | Challenging - Class 2 |
| Terminal Peak | Glacier National Park | Complex - Class 3 |
| The Cone | Glacier National Park | Complex - Class 3 |
| The Hourglass | Glacier National Park | Challenging - Class 2 |
| The Mouse Trap | Glacier National Park | Complex - Class 3 |
| The Ravens | Glacier National Park | Complex - Class 3 |
| Ursus Major | Glacier National Park | Complex - Class 3 |
| Ursus Trees | Glacier National Park | Complex - Class 3 |
| Vaux Moraines/Sir Donald/Uto Col | Glacier National Park | Complex - Class 3 |
| Vent Shaft slopes | Glacier National Park | Complex - Class 3 |
| Video Peak | Glacier National Park | Complex - Class 3 |
| West Woolsey Creek | Mount Revelstoke National Park | Complex - Class 3 |
| Wheeler Hut approach and vicinity | Glacier National Park | Simple - Class 1 |
| Woolsey Creek Road | Mount Revelstoke National Park | Challenging - Class 2 |
| Woolsey Glacier-Coursier Peak | Mount Revelstoke National Park | Complex - Class 3 |
| Youngs Pk via Illecillewaet | Glacier National Park | Complex - Class 3 |
- Date modified :