Professional Observation

Observation Details

Signs of Unstable Snow

Key Points

I toured to the Mammoth Crest to track surface warming and wetting in the upper snowpack. I observed weather on a northerly aspect at 8700 ft, 9700 ft, and 10700 ft in both directions. On the way out, I dug hasty pits at each observation site, took snowpack temperatures to a meter below the surface, and performed a few snowpack tests.

• Wind and low clouds kept elevations above 10,000 ft from thawing where I was today. The entire snowpack down to 100cm was dry and below freezing with a 3cm melt-freeze crust on the surface on all but southeast slopes, where I got tiny, stubborn rollerballs and wet snow to slide a little. Persistent weak layers from March were hard to identify. No propagating test results.
• Below 10,000 ft surface crusts began to thaw around 1030 am. Boot and ski penetration increased after noon when skiing was heavy and difficult. Chunks I threw out of my snow pits at 9700 and 8700 ft turned into rollerballs and took on mass as they rolled down the hill in wet snow.
  • At 9700 ft the snowpack was moist and below freezing 20cm below the surface at 11am. At 130pm the top 20cm was wet, and it was moist down to the crust buried 3/29 (down 50cm). The grains above that crust were no longer facets, but 2mm melt-forms. No propagating test results.
  • At 8700 ft the snowpack was moist below a surface melt-freeze crust in the moring, but it was at freezing and wet in the afternoon when it was at the melting point (0C) down to at least a meter below the surface. The 2 March crusts were easiest to spot at this elevation and they had wet layers of melt-forms (with a few rounding facets) above them. No propagating test results.
• Some unreported glide cracks are just starting to open on the Crest and on McGee. Cornices are hanging in there. There were deep runnels at all elevations. I saw lots of small to large wet loose avalanches from the past 72 hours on all aspects and elevations in the Lakes Basin. 1 on a south aspect above Barney Lakes may have occurred yesterday or just before I got a view of it at noon.
• On my drive down the hill, there were no clouds socking in the peaks like in Mammoth. Instead, there were high and hazy clouds. I saw several new (I think) small wet loose avalanches and one that might have been D2.