Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
Purcells.
Confidence
Fair - Due to limited field observations for the entire period
Weather Forecast
Wednesday: Mostly cloudy with isolated light snowfall bringing 1-3cm of accumulation, freezing levels in valley bottoms, and light northwesterly winds. Thursday: Increasing cloud throughout the day with light snow bringing another 2-5cm, freezing levels remaining in or just above valley bottoms, and winds increasing to strong southwesterlies. Friday: Continued light snow with another 2-5cm, strong southwesterly winds, and freezing levels remaining in or just above valley bottoms.
Around 80 cm of snow fell over the past week. This loads a surface hoar and/or facet layer that was buried at the end of November. Recent snowpack tests from the Invermere area gave moderate but resistant results on this weakness where it was found as surface hoar down 34cm. A bit deeper (near 100 cm down) another surface hoar layer that developed during mid-November may still be reactive; however, recent testing around the Invermere area has proved this layer to be unreactive. Near the base of the snowpack is the early November crust/facet deep persistent weakness. Recent tests throughout the region suggest that it is primed for triggering if you hit the right spot, with anywhere from easy to hard results but consistent sudden fractures.
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.
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.