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Disclaimer

This English version is a translation for reference. If it differs from the Japanese version, the Japanese version prevails. 日本語版

This Disclaimer forms part of the Terms of Service of the Alpine Avalanche Research Institute, a general incorporated association (hereinafter "AARI").

1. Information on the Service

• Avalanche records: records that posters sent to the Service
• Snow depth, snowfall, temperature and wind values: JMA AMeDAS observations, and values that AARI processed from them (Section 5)
• JMA's analysis and forecast surfaces (Analyzed Snow Depth, Analyzed Snowfall, Short-term Snowfall Forecast), and weather maps based on JMA's actual surface weather maps (Section 5)
• Maps, aerial photographs, winter satellite imagery, 3D terrain, slope-angle colour shading, and sun and shadow on the 3D terrain (Section 6)
• The slope meter (testing; Section 7)

AARI does not guarantee that this information is accurate, complete or up to date. AARI's responsibility for compensation for damages is set out in Article 15 of the Terms of Service.

2. This is not a forecast or a warning

• AARI does not hold the permit for forecasting services under Article 17 of the Meteorological Service Act. The Service does not issue avalanche, snow cover or weather forecasts or warnings.
• When the Service displays a JMA forecast (the Short-term Snowfall Forecast), it shows that it is a JMA forecast and displays the values unchanged.
• Weather maps show only actual conditions (analysis). Forecast weather maps are not shown. For forecasts, see the weather maps on the JMA website (https://www.jma.go.jp/bosai/weather_map/).
• When the Service displays calculation results of a numerical prediction model, the page states that they are not a forecast and may contain large errors.
• The colours and displays of the Service are not warnings or advisories. Warnings and advisories are issued by JMA.

3. About avalanche records

• Avalanche records are records of avalanches that posters saw. AARI may check the format of a post and obvious errors, but the content is not necessarily all correct. AARI may mark a record it has checked to show that it has been checked.
• Many avalanches that occur are not reported. A slope or a day with no record does not mean that no avalanche occurred or that it was safe.
• The location and lines of an avalanche are what the poster marked on the map. The elevation, the aspect and angle of the slope, and the place name are values calculated automatically from the Geospatial Information Authority of Japan (GSI) elevation data and other sources, and contain errors.
• A past record is what happened under the snow and weather of that time. It does not show the current state of the snow.

4. When data updates stop

• If the retrieval of data from JMA and other sources stops, the display may remain out of date. On the snow depth and snowfall page, "Updates have stopped" is shown in that case. Check the time of the values displayed.
• The Service may stop because of inspection, a failure, or the circumstances of a data provider.

5. About the snow depth and snowfall page

The snow depth and snowfall page (https://avalanche-data-base.online/v2/snow/) displays JMA AMeDAS observations, JMA's Analyzed Snow Depth, Analyzed Snowfall and Short-term Snowfall Forecast, and a surface weather map redrawn from JMA's actual surface weather maps.

• Source: JMA website (https://www.jma.go.jp/bosai/amedas/ , https://www.jma.go.jp/bosai/snow/ , https://www.jma.go.jp/bosai/weather_map/ , https://www.data.jma.go.jp/developer/)
• The 3-, 48- and 72-hour snowfall, the change in snow depth, the 24-hour maximum and minimum temperatures, the rankings, and the "Recent weather" text for each station were created by AARI by processing AMeDAS observations. The processing is limited to adding and subtracting values, taking maximums and minimums, and sorting. They were not created by JMA.
• The surfaces overlaid on the map (Analyzed Snow Depth, Analyzed Snowfall, Short-term Snowfall Forecast) display the values created by JMA without processing.
• The surface weather map is JMA's actual surface weather map (Disaster Prevention Information XML) redrawn by AARI without changing positions or pressures. The JMA XML does not specify on which side the front symbols (triangles and semicircles) go, so AARI places them based on the type of front. AARI is responsible for the editing.
• The surface weather map and the values on the map can also be shown for past times (every 3 hours). Past values are created by AARI from AMeDAS observations up to that time, using the same calculation as the latest values. The JMA snow distribution map (analysed snow depth, analysed snowfall and short-term snowfall forecast) is not shown for past times.
• JMA's observations are preliminary values, and JMA may correct them later. In addition, an AMeDAS value is the value at that observation station. It may differ from the snow on a mountain slope with a different elevation or terrain.

6. About maps, aerial photographs, satellite imagery, slope-angle colour shading, and sun and shadow

• Aerial photographs and winter satellite imagery show conditions at the time they were taken. They do not show the current state of the snow. The winter satellite imagery is a composite of images from days with little cloud, and the snow is emphasized in white.
• The 3D terrain and the slope-angle colour shading were calculated by AARI from GSI elevation data (a 5 m or 10 m grid). The shape of the snow surface and terrain smaller than the grid (small gullies, cornices, rocks and so on) do not appear. They may differ from the actual angle of a slope.
• "Sun and shadow" on the 3D terrain shows the sun position that AARI calculates for the chosen date and time, and how much sunlight each slope receives and the shadows cast by mountains, calculated on your device from GSI elevation data (a 10 m grid), coarsened to about 8–120 m depending on the area shown. The shadows are calculated from the terrain only; clouds, trees and buildings are not included. Shadows of terrain smaller than the calculation grid, and shadows of mountains farther than about 12 km, do not appear. It does not show the state of the snow or how likely avalanches are.

7. About the slope meter (testing)

• The slope meter is a page under testing. It measures or calculates the angle of a slope from the tilt and direction sensors of a smartphone and GSI elevation data.
• The measured values include errors from the sensors, errors from the grid size of the elevation data, and errors from differences in shape between the snow surface and the ground. The values of the slope meter are not a substitute for measurement and observation on site.

8. Links to external sites

Where the Service links to external sites, the linked sites are not managed by AARI, and AARI does not guarantee their content.

9. Data sources

The Service uses the following data. What AARI has processed was not created by the provider. The providers also do not guarantee the accuracy of the data.

The Service uses Leaflet (BSD 2-Clause License) and MapLibre GL JS (BSD 3-Clause License) to display maps.

10. Changes to this Disclaimer

This Disclaimer is part of the Terms of Service. Changes follow the procedure in Article 17 of the Terms of Service.

Enacted: July 21, 2025
Revised: October 19, 2026
Alpine Avalanche Research Institute (General Incorporated Association)