Snowpack depth seems to be a key piece to the avalanche puzzle. Watch for shallow areas as you approach upper treeline and alpine areas.
Confidence
Moderate - Wind effect is extremely variable
Weather Forecast
Temps will fall overnight to the -15 to -20. No snow is forecast, but as I say that I look out the window and see it snowing...flurries might give a few centimeters of new snow. The winds will continue to be from the NW, but they will slow down to the moderate range.
Avalanche Summary
We had reports of an avalanche on Snowpeak yesterday, but details are few right now. All we know for sure was it was in a shallow, alpine snowpack. There was also a fresh but distant avalanche noted today in the high alpine towards Mt Assiniboine. Likely a cornice trigger maybe a 2.5, east aspect.
Snowpack Summary
Quite a few changes last night. Firstly, the wind once again picked up and created new slabs in the alpine. Judging from how things look, these slabs are isolated in nature and mostly in immediate lee areas. Treeline was spared the full brunt of the wind so there is a bit of new snow overlying the older windslabs. Having said that, there may be slabs in wind exposed areas. Secondly, there is a hint of sun crust on solar aspects. In Alpine and treeline areas the mid pack is generally well settled with a minor shear (failure) noted on the Jan 17 layer. I say minor because the snow above isn't a slab yet and the layer is shallow. The deeper weak layers are just...deep & weak. From what we can gather, in deeper snowpack areas the bridging effect of the midpack keeps the house of cards from collapsing. In shallow areas, all bets are off. That layer is delicate and if it fails, expect a large avalanche!
Problems
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.
Wind Slabs
Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.