AVOID ALL AVALANCHE TERRAIN. It's time to rein in your terrain choices to simple, no consequence areas. Better yet, stick to the ski hill. Avoid all overhead hazard as well - avalanches have the potential to run to valley bottom.
Confidence
Moderate - Intensity of incoming weather systems is uncertain
Weather Forecast
Significant heavy snowfall (especially in the southern areas) right through Monday afternoon with moderate southwesterly winds. MONDAY: Heavy snow Sunday overnight into Monday with 35-80cms forecast / Moderate southwest wind / Alpine temperature -12TUESDAY: Scattered flurries / Light southwest wind / Alpine temperature -10WEDNESDAY: Periods of snow, accumulation 5-10cm by day's end / Light to moderate southwast wind / Alpine temperature -8
Avalanche Summary
Soft slabs from the storm snow (to Size 1.5) were very reactive to ski cutting and explosives control on Saturday. The size and distribution of avalanches will increase significantly by Monday afternoon: It's time to seriously dial back the terrain use and stick to simple, no consequence terrain. The possibility of triggering the weak faceted layers deeper in the snowpack remains a concern, and storm slabs may step down to trigger larger, more destructive avalanches. .
Snowpack Summary
Storm snow totals are taking on epic proportions near Castle mountain with upwards of 60cm falling in the past two days. Across the region, 25-60cm of new snow typically sits on wind-affected surfaces at higher elevations. This new snow is forming touchy soft slabs on all aspects in the alpine and treeline as winds were shifting on Saturday. Below 1500 metres you may find an isolated thin breakable rain crust about 1 cm thick. The snowpack is quite variable throughout the region. In deeper areas, the snowpack appears to be well settled with isolated concerns about the mid-December facet layer buried 50-100 cm deep. In shallow snowpack areas and lower elevations, the snowpack is weak and faceted. For instance, in the Elk Valley north area near Crown Mountain last week the height of snow was 90 cm with foot penetration of 80 cm; or almost to ground. In these areas, the wind has formed isolated hard slabs above weak facets and created the potential for large persistent slab avalanches.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-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.
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.