Avalanche Bulletin

Anyone planning a route in alpine terrain during winter cannot ignore the official avalanche bulletin. To make it easier to incorporate its information into trip planning, we visualized the key elements directly on the map.

What does the layer show?

Avalanche bulletin

The avalanche layer is based on the daily avalanche bulletins issued by the avalanche warning services. These official bulletins are integrated as text for all available avalanche regions. In addition, we’ve visualized the key elements of the bulletin directly on the map. This lets you identify most of the terrain‑relevant information with a single click.

Danger level

For each avalanche region, the avalanche warning services issue at least one avalanche danger level:

Level 1 – Green – Low avalanche danger
Level 2 – Yellow – Moderate avalanche danger
Level 3 – Orange – Considerable avalanche danger
Level 4 – Light Red – High avalanche danger
Level 5 – Dark Red – Very high avalanche danger
No rating – Black/White

Additionally, the danger level(s) can change over the course of the day if the weather conditions vary significantly throughout the day. Most of the time, this is associated with an increase in avalanche danger as the day progresses:

Heavy precipitation (snow or rain) developing during the day
Strong wind developing during the day
Intense solar heating from midday onward (spring conditions)

In these situations, the map will only show the earlier danger level, since routes in these conditions are typically best done in the morning.

Avalanche problems

Even more important than the simplified danger level are the prevailing avalanche problems. A detailed description of each avalanche problem — including concrete recommendations for tour planning and decision‑making — is provided in the layer.

Core zone

The areas where an avalanche problem is particularly pronounced are called the core zone. This zone applies to the specified elevation range and — within that range — especially to the indicated slope aspects.

How can the layer be used for route planning?

Danger level in planning

When you activate the layer, each avalanche region is colored according to its current danger level(s). This area‑based display already provides an important overview: depending on your experience and how much risk you’re willing to take, you can select or exclude suitable tour areas.

If you zoom further into the map, you can open the official avalanche bulletin for a region by clicking its icon.

When you activate an avalanche problem — either within a specific region or worldwide — all areas that are particularly affected by this problem today (according to the avalanche bulletin) are highlighted.

Danger Levels 1–3: Only steep terrain (>30°) within the core zone is highlighted. This minimum slope angle is physically required for an avalanche to occur.
Danger Levels 4 and 5: All areas within the reported core zone are highlighted — regardless of slope angle. Reason: Danger Level 4 is issued only on a few days each winter, as it requires an extremely dangerous combination of factors that rarely occurs. Spontaneous avalanches are typical here and can become very large, which means even gentle or distant terrain can be threatened. Only true experts should even consider touring outside secured pistes. Route options are extremely limited, since not just individual slopes but entire terrain basins must be considered as potential runout zones for spontaneous avalanches. Even backcountry experts usually restrict themselves to well‑known, often pre‑alpine terrain. Rule of thumb: If you don’t know the planned route including the large release and runout zones and the terrain traps very well, you should avoid touring in unsecured terrain at danger level 4 — this even applies to freeride terrain near ski areas.
Danger Level 5 is so rare that it isn’t even issued every winter. Roads are closed and disaster‑management measures are activated by authorities. Winter sports in affected regions are out of the question — even for experts.

CAUTION: This layer focuses on avoiding slab avalanches triggered by backcountry travelers. Statistically, more than 90% of avalanche accidents fall into this category. The release, track, and runout zones of avalanches are NOT part of the layer. Spontaneous avalanches and remote‑trigger zones are also not shown, but must still be considered in your planning depending on the avalanche situation!

What specifically does this mean for my route planning?

The highlighted areas represent potential key avalanche locations today. Depending on your experience and how much risk you’re willing to take, you should either avoid these areas already during planning or assess them carefully in the field.

In addition to the highlighted zones, you should also avoid — or carefully assess — the slope areas, gullies, and terrain depressions below the colored areas if:

Danger Level 3 or higher is issued: Spontaneous avalanches are possible here, and depending on avalanche size and terrain shape, they can reach routes further below.
The glide snow avalanche problem is present: glide snow avalanches are always spontaneous avalanches.
The wet snow avalanche problem is present: spontaneous avalanches are typical here.
The new snow or persistent weak layer avalanche problems are present: remote triggering is possible even from much flatter terrain.

Additional tools — such as our Slope Angle and the ATHM layers — support you in making informed, responsible decisions both during planning and in the field.

With a gliding snow problem, avoid not only the highlighted areas, but also the terrain below them, as it can be part of the avalanche path or runout zone.
From danger level 3 upward, also consider the terrain below the highlighted zones, since spontaneous avalanches, and in the case of new snow or persistent weak layer problems, remote triggers from flatter terrain, are possible.
With the persistent weak layer problem, remote triggers from flatter terrain are especially treacherous, as they can occur even at low danger levels and produce large avalanches.

What’s the difference to the ATHM layer — and do I still need the slope angle layer?

The ATHM layer also highlights terrain where backcountry travelers can potentially trigger avalanches. Unlike the avalanche bulletin layer, however, the ATHM layer only visualizes static terrain characteristics such as slope shape, slope size, slope angle, and vegetation. The dynamic component — the day‑to‑day changes in snowpack stability caused by the weather — is not included in the ATHM layer.

Put simply:

The ATHM Layer shows you the terrain where avalanches can generally be triggered.

The Avalanche Bulletin Layer shows you where triggering is especially likely today.

The Slope Angle Layer also remains essential for winter route planning in alpine terrain. Besides avalanche danger, there are other critical situations — sometimes mentioned in the avalanche bulletin — that the avalanche bulletin layer cannot visualize. For example, icy snow surfaces can turn steep terrain into a significant fall hazard. These critical areas can only be identified with the Slope Angle Layer, allowing you to put on the required equipment (ski crampons, or even crampons and an ice axe) in time.

The south‑facing ascent lies within the core zone of the wet snow problem, while the north‑facing descent is not affected.
Photo: Outdooractive Editors
Although the ascent is partly within the wet snow core zone, according to ATHM it isn’t typical avalanche terrain. The north‑facing descent, however, runs through typical avalanche terrain according to ATHM.
Photo: Outdooractive Editors
Even if no other avalanche problem affects the north‑facing descent, you still need to check the terrain with the slope‑angle layer (e.g., fall hazards in very steep, icy terrain).
Photo: Outdooractive Editors

Why do I still need to read the official bulletin?

On the map, only the danger levels and the core zones of the avalanche problems mentioned in the bulletin can be shown (elevation band + slope aspect + selected slope angles).

The layer does not visualize:

Expected avalanche size
Number of critical locations
Additional load required to trigger an avalanche
Hazardous terrain features outside the core zone (e.g., wind‑loaded gullies and hollows with wind‑drifted snow)
Release, track, and runout zones of avalanches

These details are only available in the text of the official avalanche bulletin and must also be taken into account during tour planning!

Coverage

The data is updated daily and comes from the official avalanche warning services:

Lawinenwarndienst Bayern (DE)
WSL - Institut für Schnee und Lawinenforschung SLF (CH)
Landeswarnzentrale Vorarlberg (AT)
Lawinenwarndienst Salzburg (AT)
Lawinenwarndienst Oberösterreich (AT)
Lawinenwarndienst Niederösterreich (AT)
Lawinenwarndienst Steiermark (AT)
Lawinenwarndienst Kärnten (AT)
Albina (AT / IT)
Aineva (IT)
Centre de Lauegi d`Aran (ES)
NVE / Varsom (NO)
Arso (SI)
Avalanche Warning Service Slovakia (SK)
Scottish Avalanche Information Service (UK)
Avalanche Information Sweden (SE)
Avalanche Warning Service Czech Republik (CZ)
Icelandic Met Office (IS)
Meteo France (FR)
U.S. Avalanche Centers (US)
Avalanche Canada (CA)
NZ Avalanche Advisory by Mountain Saftey Council (NZ)