Seeley Lake West

We set out to investigate the snowmobiler-triggered avalanche reported earlier this week. It is a large avalanche (size 2) that ran through trees. We were glad we didn't hear of anyone injured, and are grateful to the party that reported it. Avalanches are the best piece of information we have for understanding a complex snowpack. 

This avalanche, and another small one we intentionally triggered, both ran on surface hoar buried about a foot deep. Riders we talked to reported no other signs of instability today, but clearly human-triggering an avalanche is still possible if you find the right spot.

Another group we talked to reported small loose avalanches on southeasterly slopes yesterday.

Intentionally triggered a size one persistent slab avalanche on an easterly slope by stomping on a rollover.

One foot (30 cm) of low-density snow has fallen since Feb. 14th. This overlies surface hoar. In our pit on an east aspect at 7200 feet there was a 1 inch (2cm) layer of facets above the surface hoar. We had a propagating extended column test (ECTP13) with moderate taps on this layer in one of three tests. The two nearby avalanches ran on this surface hoar layer.

One and a half feet deep (50 cm) was a melt-freeze crust that was starting to facet out and lose strength.

At about 2.5 feet deep (75cm), we found the January drought surface hoar, buried on January 24th. We had two propagating extended column tests on hard taps (ECTP22, 23).