Navigating Avalanche Terrain

Navigating Avalanche Terrain
Posted by on May 8, 2017
Posted in: mapping, tips and tricks, transportation, Uncategorized

This winter I decided to prepare for my backcountry ski trips by finding routes that are lowest in avalanche danger. CalTopo was recommended to me by a volunteer with the Mount Saint Helens Institute because its MapBuilder option can show slope shading, and slopes between 34 and 45 degrees are known to be prone to avalanche. When I discovered an App that integrates CalTopo at a safety lecture, I took the data outside to see what I could learn.

GaiaGPS compiles topographic maps, satellite imagery and slope shading through providers like CalTopo and MapBox (OpenStreetMap). Because smartphones already have offline GPS capabilities, the potential money saving advantages for backcountry way-finding are huge – $20 compared to $200+.

My first mapped trip was to Mount Thielsen, where I downloaded the summer route GPX file, and then tracked my own ski path to evaluate my judgement. In the map above I’ve created four layers – topographic elevations, slope shading, summer route (blue), and my ski track (purple). Once completed, the phone interface provides an analysis of my recorded track, showing graphs of altitude gain as well as useful statistics like moving time and stopping time.

Needless to say, the best skiing coincidentally happens in the red (35-45 degrees ) avalanche zones. Here are some of my photos correlating to the peak shown above – the corniced ridge is the steep area shown in purple (46-50 degrees ), located above the blue track on the map. You can see we skinned up the yellow zone (27-29 degrees ) reaching a steeper high point of about 8,700 ft. Besides terrain incline, the trifecta (terrain-weather-snowpack) of avalanche danger includes temperature fluctuations and I was lucky to have fantastic spring snow conditions.

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My second GaiaGPS test was a multi-day trip abroad to British Columbia (below). Fortunately crossing the border beyond phone coverage did not deter the GPS function from working and I navigated to a trailhead, packed my gear and skinned along a three mile GPX track leading to a mountain hut in the Matier valley.

The accuracy of my phone GPS was spot on and led me through the moonlight to the cabin where I collapsed into a deep sleep at 11PM. During my first trial on Mount Thielsen I found recording my track drained my battery within 6-8 hours. This time I only referenced my expected route and set individual waypoints rather than recording continuously, which was much less of an energy drain on my phone.

Of course, nothing beats good local advice, and I although I did not find GPX routes for skiing, I did discover alternative resources for potential runs. Sam McCoy, a Canadian guide, created the Google Earth image below showing ascents (red) and decent (blue) lines for Matier glacier.

Below are images of the valley, you can see the Matier glacier showed signs of recent avalanche activity, photographed from the vantage point of Motel 66. Even within the course of a day the snow warms and changes significantly in saturation, stickiness and weight. I can’t say I avoided avalanche terrain as I planned, but I suppose I would have to go back to cross country skiing to really do that. Not happening.

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Post trip, my GaiaGPS app automatically syncs to an online login where I can export a PDF, look at my trip map full screen, share routes or view other publicly shared tracks.

About Yelena

Yelena Prusakova is an illustrator at Fat Pencil Studio.