Snow conditions in the Mammoth Lakes Basin

I toured up to the Mammoth crest today via the Red Cone ridge to survey current conditions after the powerful winter storm last night. New snow totals ranged from 20cm on the wind-exposed East face to 50 cm in depressions and other catchment zones.  Surface conditions were heavily wind affected throughout my tour, even in well-protected trees. In more open wind-exposed areas, large drifting, sastrugi, and a layer of low-density wind board made for less than ideal skiing, and the new snow had a distinctly upside-down feel. In well-protected trees, the wind effect was less pronounced, with a thin wind skin at most, and the skiing was pleasant boot-top powder. While I had several hand sheers fail under easy pressure in areas with the upside-down wind board, I saw very few signs of storm instabilities today. That being said, I was able to kick loose a small pocket of storm snow on a particularly steep roll over on my descent down the ridge. While some small shooting cracks were observed at this location, this particular piece of unstable snow was not very cohesive and was more reminiscent of a loose dry slide than a storm slab. 

Digging in at 10200’ on an Eastern aspect near the top of Red Cone, I found 20cm of new snow on top of a largely faceted snowpack with two distinct crust layers. (See pit profile and video) Stability tests highlighted a poor structure and a reactive, weak layer of facets below a p+ hard Melt freeze crust. While the overlying slab in this location was thin and not very cohesive, I suspect this structure could be present in many other areas.  I don’t think much more snow would be required for this poor structure to become a problem. My thoughts today went to wind loaded areas where the overlying slab will be more cohesive and substantial.

I also dug a quick pit at 9000’ on a more northerly aspect. At this location, I found a similar snow depth and structure. While I did not find the same MF crust, I was able to identify the Dec12 rain crust. The rain crust at this location was heavily decomposed and was difficult to find. While the snowpack below the new snow was comprised almost entirely of faceted grains, it was largely right-side-up, and stability tests did not identify any layers of concern.

While reports of several avalanches came in today, I did not observe any natural or skier triggered avalanches on my tour of the lake’s basin. All in all, it was a beautiful day in the mountains, and the refresh is certainly a positive development.

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