Northern San Juan

Snowpack

The photos below were taken between 1:45pm-1:55pm on Sunday 2-23-14 in US Basin on Red Mountain Pass. I triggered this avalanche on a snowmobile by traversing the snowpack during a sidehill maneuver that spanned several hundred feet. The slide occurred at approx. 1:10pm. The aspect was NE and the slope was approx. 55 degrees. The slide trigger point was just below treeline. The crown that slid was approx. 150-200’ wide and the slide ran out approx. 400-500’ in different areas. I did not measure any temperature gradients in the snowpack. I realized before I started hiking up to the crown that it really wasn’t a good idea, but I felt confident the majority of the load had left, and that the hangfire was unlikely to come down on me. I felt like an idiot when I got up there though, the crown was taller than me in spots and I knew that if even some of it fell it would probably crush me, and I wouldn’t matter that I had a lot of people watching me ready to help. The areas I was willing to hike to (not the deepest areas of the crown) measured 165-170cm deep. The fracture line from end-to-end was well over 250’ wide, and was visible from side to side, but only the middle released. It was fascinating to see that the sides only slid a couple inches, which for me seemed like a really amazing demonstration of cohesion. The slab was enormous, but much of it mostly stayed put. Another demonstration of the cohesive nature of this snow was that when I reviewed the run-out, I found entire sections of snowpack that had my tracks on them: whole 10-15/30-40’ sections that had my sidehill track perfectly intact, undisturbed by the slide down. I only had an Iphone, but I tried to capture the characteristics of the facets in some of these pictures. They were the biggest and most beautiful I’ve ever seen. At the higher point of the runout, I could have taken a five-gallon bucket and just bucketed up bathtub loads of crystals; I’ve never seen anything like it. Where I put my hand down when I was up at the crown, it felt like the depth hoar was 5-6” deep with those big facets, but I didn’t look at that for long. I got that feeling like it was time for me to get out of there.