Identify avalanche terrain quicker and easier this winter with the Slope Angle map. We brought development of the slope angle overlay in house and tapped into the US Geological Survey’s 3D Elevation Program and NASA’s Digital Elevation Model. These sources allowed us to expand our coverage globally, integrate high-resolution data, and fine-tune color details. These improvements help make picking out steep, avalanche terrain on the map a snap.
Whether you’re backcountry skiing the bowls or snowmobiling deep into the forest, add the Slope Angle layer to your favorite base map to help plan a safer route through the backcountry. If you’ve downloaded slope angle maps in the mobile app before, you will see a notification at the top of the “Saved” tab that will let you update your old maps.
Graded Color Style for Finer Details
A continuous color ramp shows terrain changes in a graded fashion, making the change in terrain easier to read on the map.
The new layer emphasizes 30 to 45-degree zones in orange and red colors, recognizing and calling your attention to the fact that these slopes comprise the starting zone for most avalanches. Less steep terrain — in the 20 to 25-degree range — is highlighted in green. Slopes steeper than 45 degrees are shaded in greyscale colors to point out the steepest terrain on the map. The grey shading also helps people with red/green confusion color blindness see the map details.
High Resolution in the US and Worldwide Coverage
The new Slope Angle layer applies the most up-to-date data to deliver insanely crisp resolution for most areas within the United States. USGS 3D Elevation Program provides the best resolution for parts of the US with LiDAR data at 1 to 3 meters. This high-resolution coverage is expanding and will be updated as the USGS releases it. Other parts of the US are covered by 10 meters of resolution through USGS NED data.
Get 25-meter resolution in Western Europe with EU DEM and 30-meter resolution elsewhere around the globe with NASA’s Digital Elevation Model. The higher resolution shows smaller terrain features that would otherwise be hidden with lower resolution data.
Warning and Limitations
Avalanche forecasting uses many tools to analyze avalanche risk in the field. Slope shading is best used for a big picture overview of terrain. All slope angle maps, including the new Slope Angle layer, fail to show micro terrain such as small starting zones. Snow features like wind pillows and cornices will not be on the map. Be prepared to use an inclinometer and other on-the-ground assessments in the field in addition to the slope angle map. Change your plans accordingly if terrain does not match up to data depicted on the slope angle layer. Educate yourself about avalanche and snow safety before traveling in any areas prone to avalanches. For more information on how slope angle maps are made, see Jeff Deems’ presentation about how these map overlays are made from the 2019 Colorado Snow and Avalanche Workshop or the article “Digital Mapping: Do You Know What Your Map Knows?” in September 2020 issue of The Avalanche Review.
How to Get the Slope Angle Layer
The new Slope Angle layer is available with a Gaia GPS premium membership. To access the layer, visit the layers menu, and select the “Features/Weather Overlays” tab. Scroll down and tap “Slope Angle.” Tap the “Add Layer“ button. Learn how to add and manage overlays here.
Pair this map with other useful backcountry skiing maps available with a Premium membership on Gaia GPS. Read up on how to use maps, including the slope angle layer, to help avoid avalanche danger.
If you’ve downloaded slope angle maps in the mobile app before, you will see a notification at the top of the “Saved” tab that will let you update your old maps.
