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Preparation for Snow Activities

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TwoNav Team
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TwoNav offers various tools specially designed to be useful in preparing for snow activities such as ski touring or snowshoeing.

For their development, TwoNav has relied on the advice of specialized institutions such as ACNA, ATESMaps, mountan guides associations such as AEGM, and rescue units such as the GRAE Firefighters and the Mountain Unit of the Civil Guard (GREIM).. 

These types of snow activities involve certain dangers, which can be very high and even put the lives of participants at risk. TwoNav strongly recommends that any user wishing to practice these sports receives proper training at centers such as ACNA (Spain), ANENA (France), or other specialized centers.

The information is divided into 4 sections:

  1. Weather
  2. Avalanche Danger
  3. Creating Offline Maps
  4. Practical Case

1. Weather

1.1 General Forecasts

As with any other outdoor sport, the general forecast is important to monitor factors such as temperature, cloudiness, precipitation, or the probability of storms. 

In these articles you can find out how the weather tools generally work:

Note: Weather maps are available in Land (coming soon to the TwoNav App). Location forecast is available in both Land and the App.

1.2 Snow Maps

Among the weather maps, we have 3 types specifically related to snow:

  • 3-hour interval forecast. How much snow is expected to fall in each interval over the coming days.
  • 24-hour accumulation forecast. How much snow will accumulate in the next 24 hours.
  • Snow coverage. Indicates whether the area is covered by snow. This is not a future forecast, but combines satellite data with forecasts to provide a map of the estimated current coverage.

The Snow Coverage and 24-hour Accumulated Snow maps are divided into the Alps area and the Pyrenees area.

 

2. Avalanche Danger

Avalanches are a major danger for snow sports. Avalanche risk control is key to carrying out activities safely. 

In this section, we will describe the following available resources:

For the development of avalanche-related resources, TwoNav collaborates with ATESMaps, an organization specialized in this type of material, and provider of the online cartography in the Pyrenees_Avalanches folder, which covers most of the aspects we will mention below for the Pyrenees area.

These maps are available for Land (version 10.6 or higher) and TwoNav App (version 6.2 or higher), and require a Premium subscription.

For other areas, there are other resources, which we will discuss in each section.

 

2.1 Bulletins

Avalanche danger bulletins are prepared daily by specialized personnel, analyzing meteorological data and field observations. 

These bulletins are prepared by each of the organizations responsible in their snow-climate area. They are regional in nature and therefore their analysis should be considered at this scale. This is during the activity planning phase.  

The user must have sufficient knowledge and training to enter avalanche terrain with the ability to analyze at the mountain and slope scale.

List of European Bulletins (EAWS)

The EAWS (European Avalanche Warning Services) brings together all these bulletins at the European level, and makes it easy to consult the general danger level on the map, as well as access the details of each bulletin. 

Land incorporates a direct access to their website (avalanches.org) to facilitate consultation of the general level in each area (Menu > Tools > Open EAWS). 

By clicking on a specific area, we can open a new window to view the specific bulletin for the area we want. 

Attention: Consulting the bulletins is a fundamental tool for safety in these areas. Training is necessary to correctly interpret this information.

Pyrenees Bulletin Map in Land

On the other hand, Land offers a map with zones and general danger levels. For now, only for the Pyrenees.

This map is useful for quickly seeing on the map which is our area of interest, and easily seeing the general danger status. Before the activity, it is necessary to read the full bulletin.

This map, Pyrenees_Avalanche_Bulletins_Plus.cwms, is found in the list of online maps, in the ‘Pyrenees-Avalanches’ folder, and requires a Premium or higher subscription.

 

2.2 Elevations

The elevation map is essential both for interpreting the bulletin and for knowing the details of the route.

In the bulletins, we will find information about the danger at different altitude ranges.

Land, TwoNav devices, and the TwoNav App can handle relief maps efficiently. 

Land and TwoNav App open the online World_Base_Relief by default. 

TwoNav devices come with a pre-installed European relief. If you need more precision, you can add more reliefs to your TwoNav account and install them on any platform (Free 3D Maps)

In Land, we can know the terrain altitude simply by hovering the cursor over the area and seeing its altitude in the status bar.

On devices or the TwoNav App, we can do the same in Pin mode (long press on the map)

On the other hand, the 3D mode will help us better understand the distribution of elevations.

 

2.3 Slopes

In general terms, avalanches occur on slopes between 25 and 45º, with the range between 35-40º being the most prone to slides.

It is essential to have a map that allows us to know the slope levels of the terrain we are going to visit, so we can avoid slopes with higher avalanche danger. 

In these maps, the areas with slopes likely to generate avalanches are usually marked, while those that do not usually generate them are transparent, so you can see the map underneath. 

Land/TwoNav have different slope maps, all of them available online:

  • ATESMaps Avalanches - Pyrenees

Pyrenees_Avalanche_Slopes_Plus.cwms map file inside Online Maps > Pyrenees avalanches. Requires Premium or higher subscription.

Recommended avalanche slope map for the Pyrenees area. This is a map specially created by ATESMaps, specialists in avalanche terrain safety. It indicates the different slope ranges that are usually conducive to triggering avalanches:

There is also a map available that includes all slope levels, not just those prone to avalanches. The file is Pyrenees_Slopes_Plus.cwms

 

  • IGN Geoportail - France

IGN_Geoportail_Pentes_Layer.cwmts file, inside Online Maps > France. Requires a subscription to IGN France Geoportail maps.

The French IGN has an online Geoportail map that highlights steep slopes. This map covers all of France and also part of the adjoining areas of the Pyrenees and France. 

This is the official slope map of the French IGN, with the usual quality guarantees.

  • Skimomap

Skimomap_Avalanche_Slopes.cosm file, inside Online Maps > World.

Avalanche-prone slope map, with global coverage.

 

2.4 Terrain Orientation

Avalanche danger bulletins include information about the mountain aspects most likely to generate avalanches at any given time. 

For example, this type of graphic will indicate which aspects are most dangerous, often also related to altitude.

 

To correctly interpret this information, it can be very helpful to have a terrain orientation map, which colors each orientation differently for identification.

Land/TwoNav have different terrain orientation maps available online:

  • ATESMaps - Pyrenees

Pyrenees_Avalanche_Orientations_Plus.cwms map file inside Online Maps > Pyrenees avalanches. Requires Premium or higher subscription.

Recommended terrain orientation map for the Pyrenees area. This is a map specially created by ATESMaps, specialists in snow sports. 

  • Skimomap

Skimomap_Avalanche_Aspect.cosm file, inside Online Maps > World.

Terrain orientation map, with global coverage.

 

2.5 Wooded Areas

Forests are an obstacle to the formation and progression of avalanches. It is useful to have a wooded areas map to take into account when planning.

  • ATESMaps - Pyrenees

Pyrenees_Forests_Plus.cwms map file inside Online Maps > Pyrenees avalanches. Requires Premium or higher subscription.

For the Pyrenees area, Land/TwoNav have the map from our collaborator ATESMaps. 

2.6 Avalanche History

Some areas have specific resources that do not exist in all snow sports areas. 

An example for the Catalan Pyrenees area is the ICGC avalanche map, which shows the avalanche history of the area. 

It is found in the list of online maps, in the ‘Spain’ folder. 

You can find more information and the legend on the ICGC website. 

If you know of other specific resources for your area, please let us know and we will try to add access from TwoNav products.

2.7 ATES Maps

In some areas, particularly in the Spanish Pyrenees, authorities have created terrain maps indicating avalanche danger according to various field-verified criteria, and classify the terrain into 3 danger levels (simple, demanding, complex).

This type of map is available for the Spanish Pyrenees, but for now cannot be consulted directly from Land/TwoNav. 

If you want to consult these maps and get more information, you can do so at atesmaps.org

 

3. Creating Offline Maps

Most of the maps we have seen are online maps, which require an Internet connection to work.

The TwoNav App can directly open these online maps, just like Land, but in remote areas you may lose your Internet connection.

On the other hand, GPS devices cannot open online maps.

To be able to use them reliably without an Internet connection, whether on GPS devices or the TwoNav App, we must have offline maps available.

In this article, we explain how to generate offline maps from areas of an online map: Create a map by selecting an area in Land

In the case of maps for snow sports, the process is the same.

We can create maps with information from a single map, but in this case, it may be especially useful to combine several maps.

For example, we can create a map combining a base map with a layer of avalanche-prone slopes.

  1. Load base map
  2. Load avalanche slope map
  3. Select area with the selection tool and click 'Create new map for this area'
        
  4. A map will be created combining information from both layers

Note: You can create a map with the current level of detail, or maximum detail. If very large areas (>100km2) are created with a lot of detail, the map creation may take a long time, or even fail.

Once the offline map is created in Land, we can send it via USB to a connected TwoNav device, or open it in the TwoNav App (How to open personal maps in the TwoNav App). 

 

4. Practical Case: Preparing a Snow Route in the Pyrenees

We will present a practical example to review the concepts from a more applied perspective.

We want to do a snow activity and have found a route that seems interesting. We load it in Land.

Next, we will analyze both the weather and avalanche danger. Since it is a route in the Pyrenees, all the avalanche maps we will use are in Online Maps > Pyrenees avalanches.

1. Weather

First, we can check the snow coverage and weather forecast.

We open the weather maps

Right-click on the time slots gadget, or on the legend, and select 'Snow Coverage (Pyrenees)'

We see that the area is covered by snow (blue)

In the same way, we check the snow forecast by time slot, and also the accumulated snow in the next 24 hours.

We also check the forecast table for that location, to get a more complete view of the expected conditions. Right-click on the map and 'Weather forecast'

 

2. Avalanche Danger Bulletin

If we know the page where the area's bulletin is prepared, we can go directly to it.

If not, Land can make the task easier.

To start, we can open the Pyrenees general view bulletin map: Pyrenees_Avalanche_Bulletin_Risk_Plus.cwms

This way we can locate our route in a specific area, and get an initial general assessment of the danger.

To find the complete bulletin, we can open avalanches.org in an internet browser, or open it integrated in Land (menu > tools > open EAWS). 

This way we will locate the area we identified earlier, and we can select it and open the detailed bulletin in a new window.

Note: We emphasize that for proper interpretation of the bulletin and in general for carrying out this type of activity, it is important to have received good training at centers such as ACNA (Spain), ANENA (France), or other specialized centers. 

 

3. Orientation and Elevation Map

In the bulletin, we saw that the danger is higher above 2400m on NW, N, NE, E, SE, and S aspects.

We activate track coloring by altitude in Land

And we see the sections of the route above 2400m

On the other hand, we activate the terrain orientation map (Pyrenees_Avalanche_Orientation_Plus.cwms) and check that our >2400m area goes through the more dangerous aspects, so we must carefully analyze that section and consider modifying the route or postponing the activity if we are not sure.

 

4. Slope Map

Since it is a snow area with a considerable avalanche danger level, we review the entire route to see if it goes through any particularly dangerous areas due to avalanche-prone slopes.

We open the avalanche slope map (Pyrenees_Avalanche_Slopes_Plus.cwms), and check that most of the route goes through areas with little risk of triggering avalanches.

We zoom in on the most critical areas to take note of them

                

We activate 3D mode for a clearer perspective

5. Wooded Areas Map

We check which parts of the route go through forested areas, both for landscape interest and for the possible protective effect against avalanches.

6. Other Resources

Depending on what is available in our area, we can combine other resources.

For example, in the Catalan Pyrenees area, we can see the historical avalanche map (online maps > Spain > Catalunya allaus)

And if we want to consult the ATES maps, we can go to atesmaps.org to see the terrain classification for that area. 

 

 7. Create Offline Map and Send It to GPS Device or TwoNav App

From all the information we have seen, we must decide which maps we want to make sure are available on the ground, on our device or TwoNav App.

7.1. Create the Map

For example, we may want to have a map that combines aerial photo with avalanche-prone slopes.

We load the 2 maps we are interested in, 

select the area we want to have offline,

 and create the new map

7.2 Send the Map to the GPS Device

To transfer it to a GPS device, connect it via USB, right-click and 'Share > Device Name'

7.3 Send the Map to the TwoNav App

The map can be loaded in the TwoNav App in several ways (e.g., run the file on the phone and select the TwoNav App to open it).

This article explains the different ways to do it: How to open personal maps in the TwoNav App

 

 

 

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