Regions
Banff Yoho Kootenay.
Increased reactivity of the Jan 17 surface hoar/crust layer is due to recent loading of storm snow. Distribution is spotty, so dig down to verify if this layer is present in your local area.
Weather Forecast
Thankfully, today is forecasted to be the coldest day. Temperatures will climb back to a somewhat reasonable level by tomorrow to about the -18 range in the valley. A clearing trend will ensue, and the wind will drop back to light from the West. No snow is forecasted for a while.
Snowpack Summary
30-45cm of recent storm snow is being redistributed into windslabs above treeline. Up to 65cm sits over the Jan.17 surface hoar which has been found up to 2300m. In shallower areas weak facets and depth hoar exist below the Dec 10 interface. In deeper snowpack this basal weaknesses is less pronounced
Avalanche Summary
No avalanches reported or observed today, however yesterday there were two skier accidental avalanches size 1.5. One was on Vermillion Peak (reported on the MIN) the other was at Bow Summit. Both were suspected to have slid on the Jan 17 Surface Hoar. No injuries or lost gear in either slide.
Confidence
Due to the number of field observations on Sunday
Problems
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.
Persistent Slabs
Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.
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.