Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Regions
Purcells.
Complex avalanche conditions at the moment. The answer to this type of avalanche problem lies in conservative terrain selection. Visit the blog for thoughts on the recent pattern of accidents in the Purcells.
Confidence
Fair - Freezing levels are uncertain
Weather Forecast
A strong, stable northwesterly flow will prevail over the province while a strong upper ridge remains offshore. The ridge should weaken somewhat on Tuesday but will still protect the province from Pacific systems.Monday: Mainly dry conditions, freezing level at valley bottom with a chance of a temperature inversion bringing warmer temperatures to upper elevations. Temperatures approaching 0 degrees or slightly warmer between 2000 and 2800m. Winds Moderate to strong from the west and northwest.Tuesday: Mainly cloudy, no precipitation, alpine temperatures -9, light west winds.Wednesday: A Pacific frontal system starts to affect the interior regions. Cloudy with light snowfall, moderate to strong west winds. Freezing level in the valley bottom.
Avalanche Summary
There have been a few different close calls with large avalanches in the north of this region in the last two weeks. Check out the incident database for more details. On Friday avalanches released naturally and with explosive control resulting in avalanches to size 3.5 with crowns up to 2 meters in depth on all aspects.
Snowpack Summary
Thursdays 20 - 40 cm of storm snow lies on top of old wind slabs and a couple of persistent weak layers that exist in the upper meter of the relatively thin snowpack. The Mid December Surface Hoar is buried around 30-90 cm. The early December facet/crust combo is buried down 50-150 cm. Both interfaces give variable results with snowpack tests, but professional operators are treating them with caution.A bigger concern, especially in the Northern part of the region is a layer of weak sugary depth hoar crystals at the base of the snowpack that lie above a crust from early October. Several large avalanches in the last two weeks have been attributed to failures at this layer. Wide propagations on relatively gentle terrain have been noted, as well as a tendency for seemingly disconnected slopes to become connected by one large avalanche.
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.