For most folks that have been in the backcountry lately it is hard not to notice the collapsing in the snowpack. Other than a few avalanches in the past week, this has been our prominent ‘obvious clue’ as to the weak snow lying 12-18” below the surface. If you look at the two observations sent in yesterday, both highlight collapsing (or whoomphing). You can see them HERE and HERE. Other red flags are found by digging in the snow. However, a collapse trumps all and essentially means that if a slope is steep enough chances are it will avalanche.
With weak layers in the pack that are hard to assess from the surface, keeping with safe travel practices will help to hedge your bets if riding/skiing on steep slopes. These include watching your partners, exposing only one person at a time and having an escape route planned if the slope avalanches.
Below is a cross section of the snowpack at 3,200′. You can see a vertical crack in the ‘slab’ and the weak snow (lighter colored) below a crust. This if from a snow pit on Magnum, SW facing. – more details and video HERE.
We received 2-3″ of snow from Friday night that was blown into drifts on the ridgelines. Cornices grew a bit with this event and some small to medium natural cornice failures were seen yesterday. This snow has shown signs of bonding well with the surface and is now part of the ‘slab’ mentioned above.
Below treeline the slab is losing its cohesion and the pack is unsupportable. Though there is some localized collapsing in the alders, triggering an avalanche is unlikely.
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