Scout avalanche terrain easier than ever before. We’ve updated our Slope Angle map with the latest highest resolution 1-meter LIDAR DEM data from the USGS. This data is the gold standard for slope angle shading, rendering our Slope Angle map crisper and clearer for your winter adventures.
Gaia GPS users primarily use our Slope Angle map in winter to avoid avalanche-prone terrain. But hikers, mountaineers, and bikepackers use it year-round to find the easiest path over mountain passes. Photographers and adventurers turn to this map to find unique rock features and waterfalls. Whatever your objective and mode of travel, you can now enjoy the highest resolution slope angle data, wherever it’s available.
Meet the Slope Angle Gold Standard: Lidar
Last year, we developed our Slope Angle map 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.
Now we’ve updated the map even further with the best data available on the planet: LIDAR DEM. Harnessing a laser scanner, Global Positioning System (GPS), and Inertial Navigation System (INS), Light Detection and Ranging (lidar) technology produces high-resolution models of ground elevation within an accuracy of 10 centimeters, or four inches. This means our Slope Angle map contains more accurate data than ever before while also pulling out more of those smaller terrain details that can be easy to miss.
Lidar Coverage Continues to Spread Across the US
The updated Slope Angle map uses the latest lidar data wherever it’s available. Check out the map above for a full view of lidar coverage. As you can see on the map, avalanche-prone regions in the northeast, California, and the Pacific Northwest enjoy excellent lidar coverage.
We’re still waiting for the USGS to supply full lidar coverage of the mountain west. The USGS hopes to complete its collection of lidar data for all of the U.S. and its territories soon; see the status map. Thanks to its high cloud cover and remoteness, Alaska uses Interferometric Synthetic Aperture Radar (IfSAR) instead.
Graded Color Style Picks up the Details
A continuous color ramp shows terrain changes in a graded fashion, making terrain features a snap to read on the map.
The map 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.
Identify Avalanche Terrain Worldwide
While LIDAR DEM does not cover the entire US, our Slope Angle map continues to provide not just country-wide, but also worldwide coverage using the highest quality data available from the US Geological Survey’s 3D Elevation Program and NASA’s Digital Elevation Model.
Whether you’re backcountry skiing the bowls or snowmobiling deep into the forest, add the Slope Angle layer to your favorite global base map like Gaia Winter or Satellite Imagery to help plan safer winter routes through the backcountry.
Keep in mind that you can tweak the opacity of the Slope Angle overlay to your needs. Turn the opacity down to reveal underlying terrain details, or dial it up to more clearly view slope steepness.
Warnings 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 updated 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 the terrain does not match up to the 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 Map
The 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.