The Avalanche Terrain Exposure Scale (ATES) layer classifies terrain based on the terrain’s potential for producing avalanches. The five categories (outlined below) provide a high-level overview of avalanche terrain, and should be used in conjunction with the local avalanche forecast to determine the most appropriate terrain to ski on a given day.

You can access Avalanche Terrain Exposure Scale (ATES) layers in the Basemaps and Map Layers Menu. Click here to learn how to use the Basemaps and Map Layers Menu.

Avalanche Terrain Exposure Scale (ATES) layers are available in any Map Mode, but work best when the app is in Snow Mode. Click here to learn more about changing Map Modes.

Avalanche Terrain Exposure Scale (ATES) layers are different than the Avalanche Forecast layer. Click here to learn more about the Avalanche Forecast layer.

Table of Contents:

Avalanche Terrain Exposure Scale layer.
Avalanche Runout layer.
Avalanche Potential Release Area layer.

Avalanche Terrain Exposure Scale layer

Green - simple.

image 2.png

Exposure to low-angle or primarily forested terrain. Some forest openings may involve the runout zones of infrequent avalanches and terrain traps may exist. Many options to reduce or eliminate exposure.

Blue - challenging.

image 3.png

Exposure to well-defined avalanche paths, starting zones, terrain traps, or overhead hazard. Options exist to reduce or eliminate exposure with careful route-finding.

Black - complex.

ATES complex.png

Exposure to multiple overlapping avalanche paths or large expanses of steep, open terrain. Sustained exposure to overhead hazard. Many avalanche starting zones and terrain traps with minimal options to reduce exposure.

Red - extreme.

ATES extreme.png

Exposure to very steep faces with cliffs, spines, couloirs, crevasses, or sustained overhead hazard. No options to reduce exposure and even small avalanches can be fatal.

Disclaimer - ATES is a useful tool for making big picture decisions about avalanche terrain, and providing a visualization for avalanche terrain that incorporates more than just slope angle. However, the autoATES model is ultimately an approximation, and you should always make your own terrain evaluation when in the mountains, and incorporate other factors such as the Avalanche Danger Rating issued by your local avalanche center into your decision making.

Avalanche Runout layer

The Avalanche Runout layer uses a runout model called FlowPy. FlowPy accounts for forest density, potential release areas, slope angle, and an elevation model. FlowPy generates the theoretical runout path of every potential avalanche release area until reaching its designated alpha angle. The alpha angle is the measurement of how far an avalanche could run. An alpha angle is defined as the angle from horizontal from the toe to the crown of an avalanche.

Runout probability - lowest.

Runout lowest.png

Runout probability - lower.

Runout lower.png

Runout probability - low.

Runout low.png

Runout probability - high.

Runout high.png

Runout probability - higher.

Runout higher.png

Runout probability - highest.

Runout highest.png

Disclaimer - Models generated from geospatial data should only be used as a guide and are best suited for high level decision making. Consult your local avalanche forecast and ground truth terrain in the field before entering avalanche terrain.

Avalanche Potential Release Area layer

The Avalanche Potential Release Area (PRA) layer estimates the probability that an avalanche can initiate on a slope. The PRA is a statistical analysis of terrain characteristics accounting for details like slope angle and forest density. Darker shades of purple indicate a lower likelihood of avalanche release and brighter yellows indicate a higher likelihood of avalanche release.

Release probability - lowest.

Release lowest.png