Regions
Kootenay Boundary.
Conditions like these frequently lead to avalanche accidents. Stay disciplined with your approach to the mountains during the holiday weekend.
Weather Forecast
Synopsis: The storm to strong cold ridge pattern seems to be stuck on repeat. Looks high and dry as yet another ridge of high pressure takes over provincial weather for the foreseeable future.Friday: Freezing Level: Valley Bottom; Precipitation: Nil; Treeline: Light, NW | Ridgetop: Moderate, NWSaturday: Freezing Level: Valley Bottom; Precipitation: 0-3mm | 0-5cm; Wind: Treeline: Light, SW | Ridgetop: Strong, W/NWSunday: Freezing Level: Valley Bottom; Precipitation: Nil; Wind: Treeline: Light, NE | Ridgetop: Moderate to Strong E/SE
Avalanche Summary
Although there isn't any new activity to report from Wednesday, there's been quite a bit of avalanche activity since Sunday featuring remote triggers, human involvements and plenty of naturals running on all aspects to size 2.5 on the Mid-December rain crust/surface hoar interface.
Snowpack Summary
30 - 70 cm of recent storm snow is consolidating into a slab above a thick rain crust / surface hoar combo that extends as high as 2400 m. Natural activity on this layer has slowed way down but it is now primed for human triggering. High elevation north facing slopes do not have the rain crust, but are still reported to have touchy buried surface hoar. On these slopes, deeper facets or buried surface hoar from earlier in the month may also be lurking. At the base of the snowpack, a crust/facet combo has become less likely to trigger, although a recent avalanche that occurred on this layer near Rossland indicates this layer should remain on our radar on steep, smooth terrain at treeline and in the alpine.
Problems
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.