Les Rasses – Sainte-Croix

Altitude zone

Avalanche and alpine dangers can change dramatically with elevation. The higher you get the more complex the terrain gets.

Low altitudes

This is the zone below 1000 meters. Here you will find mostly broadleaf trees and alpine meadows. This is where the winter is shortest and the terrain is mostly developed by humans. You will find mostly simple terrain here.

Intermediate altitudes

This is the zone between 1000 and 2000 meters. Broadleaf trees no longer grow here, but you will find loads of pine trees and larches that might give you some protection during severe storms and huge dumps. Mid mountain is also the place where you will find alpine meadows. Mid-mountain mostly offers simple and challenging terrain.

Higher altitudes

This is the zone between 2000 and 3000 meters and in general above treeline. There might be some small bushes or a random tree, but the area is mostly bare, with many rocks and very few alpine meadows. There are some glaciers in this zone, especially above the 2500-3000 meters. This zone often deals with heavy winter storms, needs more snow to be skiable and has a lot of avalanche activity. Due to the altitude more snow falls over the course of the season and the wind is very strong. It is often much colder than the intermediate and lower altitudes, so weak layers in the snowpack will persist for a longer period of time. You will find mostly a mix of challenging and complex terrain here.

High alpine

This is the zone above 3000 meters and the most bare zone in the mountains. It is even more exposed than the higher altitudes. There are many glaciers and this zone often deals with the most heavy winter storms. You will find mostly complex terrain here.

Use the altitude zone map in combination with the actual avalanche bulletin to define safer slopes already before you enter the backcountry.

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The indicated values on the map must, of course, be assumed to be approximate. They were calculated from digital terrain models. Liability claims for the representation of altitude zones cannot be asserted.

Slope angle

Nothing better than steeps, but steep pitches can also be dangerous. Slope angle, or incline, is one of the most significant terrain characteristics that determines whether an avalanche can occur.

Steeper than 30 degrees

Most winter sport related avalanches occur at slope angles steeper than 30 degrees. According to avalanche forecast standards and common risk management theories we categorized the dangerous slope angles into 4 classes:

• Steep slopes: steeper than 30°
• Very steep slopes: steeper than 35°
• Extremely steep slopes: steeper than 40°
• Super extremely steep slopes: steeper than 45°

The classes above are drawn onto the map. Most avalanche accidents happen on slopes between 35 and 45 degrees—exactly the type of slope that is most fun to ski.

If you want to ride safely make sure that you are riding slopes according to common avalanche risk management theories. When you use the actual avalanche forecast in combination with the slope angle maps you are able to define safer slopes already before you enter the backcountry.

Want to learn more?

The indicated values on the map must, of course, be assumed to be approximate. They were calculated from digital terrain models. Liability claims for the representation of gradients over 30° cannot be asserted.

Slope aspect

Radiation from the sun influences snow temperature which, in turn, plays a role in determining the strength of the snow. Warmer temperatures allow for greater bonding between individual layers in the snowpack.

North vs. south facing slopes

Slopes shaded from the sun stay cooler, inhibiting beneficial bonding among layers, and are generally more prone to avalanches during cold winter-like weather. Conversely, during warm spring-like weather, sun-exposed slopes often present a higher risk, because of weak snow due to rapid warming and melting.

North facing slopes

A north facing slope falls to the north. If you are standing on a mountain summit looking towards the north (with the sun on your back at midday), the north facing slope lies immediately in front of and below you. In mid-winter, steeper north facing slopes are shaded by the mountains for long periods and therefore not exposed to any direct solar radiation. In such aspects, settling and bonding usually occur only slowly.

South facing slopes

A south facing slope falls to the south and therefore receives sun regularly, even in mid-winter. As a consequence, the snow generally settles faster and bonds more effectively on such slopes. In the mornings, sunshine first strikes the east facing slopes. The last sunshine of the day strikes the west facing slopes.

As a result west to north-east aspects are more prone to avalanches than aspects in the south during early- and mid-winter. Use the slope aspect map in combination with the actual avalanche bulletin to define safer slopes already before you enter the backcountry.

Want to learn more?

The indicated values on the map must, of course, be assumed to be approximate. They were calculated from digital terrain models. Liability claims for the representation of slope aspects cannot be asserted.