Observation: Public

Observation Details

Signs of Unstable Snow

Observations

This morning, Pro Guiding's AIARE 2 class noted faceting on the south aspect of the snow lake divide at around 4500ft (1-2mm near-crust facets under the crust).
As we continued to move we noted similar conditions at 4500 feet on the north aspect, though this became less pronounced as we climbed to 5200ft along the ridge east of chair peak (0.5mm SH at 5200ft, North Aspect).

At the bottom of the north slope of chair peak at 4100ft we dug a quick pit on a northern aspect and conducted a compression test which failed on the 21st strike (CTH21) , at which point we noted Q1 planar shear and SH/faceting measuring 2-3mm at a depth of 35cm. The results of the compression test were congruent with results we found yesterday on 1/28 at the roughly same altitude on a northern aspect underneath Dave's at 4,167 feet.

Upon returning up to the Snow Lake Divide, we stopped to do another quick compression test at 4,500ft to see whether the issue we saw down near lake level persisted at higher altitudes. We didn't see a definitive point of failure and found that the upper layers of the snowpack (10-15cm down) were collapsing in on themselves, but were difficult to move/unlikely to shear.

Given the results of our tests, we're unsure of the future reactivity of the snowpack but found it worth noting the surface hoar--If it stays cold until the next forecasted snowfall later this week and gets buried, it may create a persistent weak layer in the snowpack.