Professional Observation

Observation Details

Signs of Unstable Snow

Key Points

We toured from the top of J 7 into the alpine with two goals today. We were hoping to evaluate recent wind deposits and to see if we could find areas where these slabs may be sitting on old weak persistent grains. We also hoped to evaluate more solar terrain for signs of warming.

On the east face of San Joaquin mtn, we found several areas with recent wind deposits atop older wind board. While in isolated areas we found firm snow on top of less firm snow (upside down) in general we found these recent deposits to be right-side up and well bonded.

We dug several quick pits looking for persistent grains and areas with thiner more breakable wind board at the base of recent deposits but we were unable to find this structure in this area. We did identify a shear plane at a density change within the more recent wind load. (4F/1F breaking on decomposing fragmented grains) However our tests suggest this layer is gaining strength and becoming unreactive.

We also traveled on several solar aspects at a variety of elevations today. We observed moist/wet surface snow as high as 11000′ today and we saw several signs of recent warming including sun crusts, a couple fans of recent rollerballs, and two recent loose wet avalanches. however, we estimate these slides and the fans of rollerballs occurred during the day yesterday. We saw no signs of instability today despite the warm temperatures and light winds.