Avalanche Forecast
Regions: Purcells.
There are a few avalanche problems to look out for, find details on where they exist and how to avoid them in the second tab. Keep the temperatures in mind, pay attention to the daylight and leave plenty of time to get home safely.
Confidence
Moderate - Recent weather patterns have resulted in a high degree of snowpack variability within the region.
Weather Forecast
The weather forecast shows a distinct split between north and south of the region. Coldest temperatures and northwest wind will be felt in the north, while southern areas will be a few degrees less cold and wind will stay southwesterly until Tuesday.
Sunday night: Mostly cloudy with scattered flurries, 5 cm. Light wind. Treeline temperature around -18 C.
Monday: Mix of sun and cloud. Light to moderate northwest to westerly wind. Treeline temperature around -20 C.Â
Tuesday: Mix of sun and cloud. Light to moderate northwest wind. Treeline temperature around -22 C.Â
Wednesday: Mix of sun and cloud. Light variable wind. Treeline temperature around -25 C.Â
Avalanche Summary
On Saturday, a natural cycle of loose dry avalanches size 1.5 were observed running far and fast around treeline in high snowfall areas. An explosive controlled size 2 cornice triggered a wind slab on the slope below near Golden.
On Friday, size 1 wind and storm slab avalanches were reactive to skiers and explosives, additionally a couple of natural size 1 wind slab avalanches were reported on a northeast aspect at 2450m.
Explosive work near Invermere continues to produce avalanches on the reloaded bed surface of the crust-facet layer, found 40-70 cm deep in that area.
Snowpack Summary
Variable wind direction has resulted in redistribution of 20-60 cm of recent snow at upper elevations. The recent snow may sit over a layer of weak surface hoar crystals at treeline and below.Â
The upper snowpack overlies a substantial crust from early December. This crust is approximately 60-120 cm below the surface, 10-30 cm thick on average, and is present across all aspects to at least 2300 m. A layer of weak facets (sugary snow) has been reported above this crust. Snowpack tests are generally showing hard results on this interface.
A late October facet/crust layer of concern sits at the bottom of the snowpack above 1900m. Although this layer has been trending less reactive, it remains on our radar.
The snowpack depth at treeline is around 120-250 cm. The deepest snowpack can be found in the southern half of the region.Â
Terrain and Travel
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Be aware of the potential for loose avalanches in steep terrain where snow hasn't formed a slab.
- Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
- Good day to make conservative terrain choices.
Avalanche Problems
Wind Slabs
Wind slabs likely remain reactive to human triggers, especially where they sit above a surface hoar interface. Watch for cracking or visibly loaded pockets of snow in leeward terrain features like below ridge crests and roll-overs on all aspects.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1 - 2
Persistent Slabs
A layer of weak facets (sugary snow) can be found down 40-120 cm over a crust that formed in early December. This layer has shown some reactivity in snowpack and explosives tests. New snow or smaller avalanches may add enough stress to trigger a persistent slab.
At the base of the snowpack above 2200 m, a layer of depth hoar lingers. Avalanches-in-motion have the potential to step down to this layer.
While the weight of a person is less likely to trigger layers of this depth, it still may be possible where the snowpack transitions from thick to thin, such as near rocky outcroppings.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Unlikely - Possible
Expected Size: 1.5 - 3