Learn to read an avalanche forecast — stay safe on your skis

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An avalanche is the main danger while skiing and snowboarding in the mountains. It is the sudden fall of large amounts of snow from steep mountain slopes into valleys, which also lifts a huge mass of snow into the air and carries rocks, trees, and other things with it. To avoid being in the path of this extremely dangerous weather phenomenon, you need to know how to read an avalanche forecast and warnings. In this article, we will understand what it is and where to get it.

What is an avalanche forecast meaning?

An avalanche forecast is a forecast with the purpose of warning about the possible formation of this weather phenomenon and its fall from mountain slopes. In particular, three main factors are taken into account when making an avalanche forecast: the snowpack stability; the probability of avalanche formation; and the size and distribution of possible avalanches in a particular area. Avalanches can be separate phenomena, or occur in series — one entails another, which is even scarier. 

It is important to understand right away that the avalanche forecast is made for the mountain slopes, not the entire vast area of the ski resort or a ski village, and is general for a certain period of time, which is subject to change just like the regular weather or snow forecast. The avalanche forecast is also updated with a certain frequency, which is generally noticeably less than that of regular weather forecasts. For example, instead of two to four updates per day, they are made every few days. From there, pay attention to the date of the avalanche forecast first. But it’s usually one avalanche forecast per day in the case of major avalanche centers.

Special meteorological and rescue government agencies make the avalanche forecast. In North America, these are the three main organizations: the American Avalanche Association (AAA) and the National Avalanche Center (NAC) in the US, and the Avalanche Canada Foundation (ACF). In Europe, it is the European Avalanche Warning Services (EAWS). In North Asia (Russia, Japan, South Korea, and China) — local similar services, depending on the country.

The avalanche forecast has two main parts:

• Avalanche Danger Scale (ADS), which is a digital and color system to warn of avalanches.
• Avalanche warnings and watches, which are ssued by the same services. They contain additional and more detailed information about avalanches that is not in the general forecast, as well as the period during which an avalanche is expected — usually up to 24–48 hours. Hence, when reading an avalanche forecast you need to consider both: the scale and the warnings.

Kevin Schmid / Unsplash

How to read an avalanche forecast and danger scale?

North Americans and Europeans have their own avalanche danger scales. The first is called the North American Public Avalanche Danger Scale (NAPADS), and the second is the European Avalanche Danger Scale (EADC). The scales are almost identical and only differ in the description of one or another level of danger.

Each of the scales consists of five categories of avalanche danger: 1 — Low (green), 2 — Moderate (yellow), 3 — Considerable (orange), 4 — High (red), and 5 — Extreme (black). Each of these levels is also illustrated by a special sign, a diamond with another special sign, and a drawing of an avalanche of different sizes. They are followed by tips on traveling in an avalanche-prone region, the likelihood of avalanches, and their size and distribution. However, the European scheme contains some additional details, such as snowpack stability, avalanche fatalities (%), and some others.

So, let’s take the scale for the US and Canada and add to it some useful details from the scale for Europe to get a universal one for any place in the world:

Low avalanche danger level (1) — Generally safe / stable: green, checkmark, no avalanche

• Travel advice: watch for unstable snow on isolated terrain features
• Snowpack stability: well bonded and stable in general
• Likelihood: natural and human-triggered avalanches are unlikely
• Size and distribution: small avalanches in isolated areas or extreme terrain
• Typical danger signs: rarely any danger signs
• Avalanche fatalities: 5%
• Forecast for: 20% of the winter season

Moderate avalanche danger level (2) — Heightened on specific terrain features: yellow, exclamation point, little avalanche

• Travel advice: evaluate snow and terrain carefully and identify features of concern
• Snowpack stability: only moderately well bonded on some steep slopes; otherwise well bonded in general
• Likelihood: natural avalanches are unlikely, but human-triggered avalanches are possible
• Size and distribution: small avalanches in specific areas, or large avalanches in isolated areas
• Typical danger signs: often you get no danger signs, but that does not necessarily mean it is safe. Pay extra attention if a Persistent weak layer is one of the avalanche problems
• Avalanche fatalities: 30%
• Forecast for: 50% of the winter season

Avalanche Danger Scale. Valerya Milovanova / Windy.app

Considerable avalanche danger level (3) — Dangerous: orange, two exclamation points, a medium-sized avalanche

• Travel advice: careful snowpack evaluation, cautious route-finding, and conservative decision-making are essential
• Snowpack stability: moderately to poorly bonded on many steep slopes
• Likelihood: natural avalanches possible, but human-triggered avalanches likely
• Size and distribution: small avalanches in many areas and large avalanches in specific areas, or very large avalanches in isolated areas
• Typical danger signs: recent avalanche activity, cracking, “whumpf” sounds. Remote triggering of avalanches is typical, especially if a Persistent weak layer is one of the avalanche problems
• Avalanche fatalities: 50%
• Forecast for: 30% of the winter season

High avalanche danger level (4) — Very dangerous: red, X sign, a major avalanche

• Travel advice: travel in avalanche terrain is not recommended
• Snowpack stability: poorly bonded on most steep slopes
• Likelihood: natural avalanches likely, but human-triggered avalanches very likely
• Size and distribution: large avalanches in many areas, or very large avalanches in specific areas
• Typical danger signs: widespread recent avalanche activity, cracking, and “whumpf” sounds. Remote triggering of avalanches is typical
• Avalanche fatalities: 10%
• Forecast for: only a few days throughout the winter

Extreme avalanche danger level (5) — Extraordinarily dangerous: black, X sign, a very large avalanche

• Travel advice: avoid all avalanche terrain
• Snowpack stability: poorly bonded and largely unstable in general
• Likelihood: natural and human-triggered avalanches are certain
• Size and distribution: very large avalanches in many areas
• Typical danger signs: NA
• Avalanche fatalities: NA
• Forecast for: very rarely during the winter season

Note: Moderately steep terrain are slopes shallower than 30 %, steep slopes — 30+ %, very steep, extreme terrain — 40+ %.

Matea Nikolina / Unsplash

Where to get an avalanche and snow forecast?

As with the regular weather forecast, all of the above is presented to winter sports fans in several popular formats, including avalanche forecast tables and interactive avalanche maps, in which colors based on avalanche danger scale mark the regions where there is a high probability of this weather phenomenon occurring.

You can get avalanche forecasts and maps on the official websites of the above-mentioned organizations or directly on the websites of the regional avalanche centers, of which they are composed. For example, in the U.S. there are more than 20 of them in the most mountainous states starting with the Colorado Avalanche Information Center (CAIC), as the main ski region of the country. In Europe, these would be Alpine countries: France, Italy, Switzerland, Austria, Germany, Slovenia, and others.

Avalanche danger map for North America

Avalanche danger map for Europe

There are also avalanche bulletins — another format for presenting avalanche forecasts, including warnings and watches, as well as general weather forecasts and other information — something like a one-page newspaper created for skiing and snowboarding fans.

A good example is the avalanche bulletin of February 6, 2023, from the Livigno Ski Resort — the largest in the Lombardy region of northern Italy. An archive of several years’ of avalanches forecasts is also available on the Livigno website, from which it becomes clear that at the resort it is made on average every other day. You can also sign up for their newsletter to receive the forecast to your inbox.

So yes, if you're more comfortable, you can also find an avalanche forecast on ski resort websites, which take information from official avalanche centers as a basis.

Livigno Ski Resort avalanche bulletin

It is also difficult to imagine an avalanche forecast without a snow forecast, which contains various weather elements associated with this natural phenomenon, as well as many general ones.

In the Windy.app, there is a whole Snow Weather Profile, where you can get a preset of 10+ weather parameters, indexes, data, and charts created especially for winter sports like snowshoeing, skiing, snowboarding, ice fishing and other. In particular, in the profile you can get:

• General weather condition
• Air temperature at the top and bottom stations of a ski resort, as well as in the middle
• Cloud coverage
• Rain ans snow chart
• Fresh snow for the same altitudes as written above
• Snow depth
• Last snowfall date
• Freezing level chart
• Wind speed, direction and gusts

Snow Weather Profile in the Windy.app for iOS

Weather elements of the Snow Weather Profile in the Windy.app for iOS

To set up Snow Weather Profile:

1. Go to your favorite or the nearest spot in the app.

2. Open Snow Weather Profile by an icon right to weather forecast modes.

3. Get weather forecast for the next 10 days.

The precipitation and wind forecast for the ski resort and the region in which it is located can also be viewed visually on the Weather Map. To do this, click on the map icon at the top of the screen in the widget and select the Precipitation layer on it.

Precipitation Map of the Dolomites in the Windy.app for iOS

However, in addition to the snow forecast, we also recommend checking the real-time weather from the nearest weather station as well as weather history.

Weather stations for ski resorts

In the Windy.app you can find weather stations right on the spot screen. It includes information about air temperature and wind. You can also get the forecast for the station as a spot. To do so, click on the "Get the forecast" icon. More: you can compare wind data from the weather station with the forecast. Click on the "Detailed analysis" icon and check the whine line in the comparison chart in the forecast table.

Weather station in the Trentino-Alto Adige region of Italy in the Windy.app for iOS

Snow history for ski resorts

Another useful thing in the Windy.app is weather history for ski resort with precipitation data on the particular day a year ago, several years ago, a decade ago as well as the average values for months and years.. This information will help you predict the snow on the day you need it. Again, there is no guarantee that if there was snow in this area on this day every year during the last 10 years, it will be the same this time, but it increases the chances a little bit.

In some other resources you can also find information about the snowfall in particular, including the snowiest week of the year at the ski resort, the number of snowy days in a week, the average snow on this day based on weather data for the last years, and other historical data.

Precipitation history in the Windy.app for iOS

Text: Ivan Kuznetsov

Cover photo: Kevin Schmid / Unsplash

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