Touchy new wind slabs are expected with the progression of the storm and the region continues to deal with a persistent slab problem.
Western areas of the region may see larger snowfall amounts. If more than 25 cm of new snow is observed, the hazard should be treated as HIGH.
New wind slab formation is expected on Monday with the incoming storm system. These new slabs may overlie a weak surface and could become touchy very quickly.
A persistent slab problem formed by a crust down 60-100 cm has created a low likelihood, high consequence scenario that is difficult to forecast. Avoid likely trigger spots such as steep, rocky slopes with a shallow or thin to thick snowpack.
A storm system is forecast to bring substantial snowfall to the region on Sunday night and Monday with strong winds. Snowfall amounts are expected to be greatest towards the south and west of the region.
Sunday night: Snowfall 5-10 cm, moderate to strong SW wind, treeline temperature around -14 °C.
Monday: Snowfall 10-20 cm, moderate to strong SW wind, treeline high around -12 °C.
Tuesday: Unsettled conditions with snow flurries and sunny breaks, light to moderate SW wind, treeline high around -15 °C.
Wednesday: A mix of sun and cloud, light to moderate NW wind, treeline high around -20 °C.
On Saturday, explosives triggered a size 1.5 wind slab. On Friday, explosives triggered a size 2.5 wind slab avalanche that stepped down to the persistent slab layer on a SE aspect near treeline. On Thursday, a natural size 2 wind slab was reported on a SE aspect near treeline.
On Monday, new wind slabs are expected to form with the incoming storm system and strong winds. These new slabs will sit on a weak snow surface and may be very reactive. The persistent slab problem remains a concern and the weight of the new snow may increase the reactivity of these deeper layers. Smaller wind slab avalanches also have the potential to step down to deeper layers resulting in very large avalanches.
The new storm snow buries a highly wind affected snow surface and widespread facets from the recent cold conditions which is expected to create a weak bond with the new snow. The new snowfall is expected to be accompanied by strong winds and reactive new slabs are expected in wind loaded terrain.
The most notable layer of concern in the snowpack is a crust that was formed in early December and is now down 50-120 cm. In the past week, we have seen explosive triggered activity on this layer as well as snowpack tests that have shown that the layer remains reactive. Neighbouring regions have seen very large avalanches on this layer over the past week. This layer has created a low likelihood, high consequence scenario which is best managed through conservative terrain choices and disciplined backcountry travel techniques.
