Professional Observation

Observation Details

Signs of Unstable Snow

Key Points

I went to the Mammoth Crest to look at wind slabs near and above treeline and see if I could find the buried surface hoar layer reported near Red’s Lake on 2/8.

• Northeast winds were strong to extreme above treeline in the Mammoth Area. I saw blowing snow off Mammoth Mountain, the Ritter Range, the Mammoth Crest, and the Silver Divide all day. If anything, wind slabs were forming more readily at treeline than in the alpine. I easily got cracking on test slopes in fresh drifts on multiple aspects. These were all 6 inches thick at the most and broke on a soft layer of fragmented grains and small surface facets. At the crest, the eroded snow was forming sandy wind buff more than slabs.
• I dug a test pit on a sheltered, north-facing slope below treeline where I had seen small surface hoar on my last trip to the area on 1/26. I found a layer of decomposing snowflakes and 2 mm surface hoar buried 25 cm below the surface. I got mixed test results on this layer. I got no collapsing or shooting cracks on steep slopes nearby. (see pit photos)
• Solar aspects, including true east, had a melt-freeze crust all the way up to 10,400 feet. Exposed areas near and above treeline are again heavily wind-affected. I found 10-15 cm of soft (F) surface facets in sheltered areas facing north.