Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Sunshine, West Side 93N.
Finding areas where there is no significant wind effect and/or lingering wind slab will lead you to the safest and most enjoyable travel. As the cold continues to weaken the snowpack, skiers/riders in steeper terrain features report triggering sizable loose dry avalanches.
Confidence
High
Avalanche Summary
On Thursday & Friday, Sunshine Village reported up to size 1.5 windslab avalanches with explosives and ski cuts. They were 30-50 cm deep hard slabs failing on a weak facet layer with propagations up to 25 m.
Also on Friday, sizable loose dry avalanches were skier triggered in steep terrain near Lake Louise.
On Tuesday we investigated the Quartz skier accidental wind slab avalanche, triggered from a shallow spot in 48° terrain.
Snowpack Summary
Last week's storm snow has been redistributed into now aging wind slabs, which sit on top of the Jan 30 interface. Specific areas exposed to the wind may also have strastrugi. The mid-pack is generally weak with facets, while depth hoar over a crust forms on an even weaker base. The snowpack is the weakest in eastern areas where snow depths are low. In these areas, the basal weaknesses should be carefully considered. Here is a representative snow profile taken on Wednesday
Weather Summary
Friday night: Cloudy periods with scattered flurries without much accumulation. Alpine temperature: Low -17 °C with Light westerly ridge wind.
Saturday: Mix of sun and cloud, scattered flurries without much accumulation. Alpine temperature: High -14 °C. Light ridge NW wind becoming SW.
Sunday: Cloudy with scattered flurries. Alpine temperature: Low -17°C, High -13 °C. Ridge wind light South.
Terrain and Travel Advice
- Be careful as you transition into wind-affected terrain.
- Be mindful that deep instabilities are still present in the snowpack.
- Closely monitor how the new snow is bonding to the old surface.
Avalanche Problems
Wind Slabs
Lingering hard wind slabs exist on alpine lee features. Potential failure planes are old weak facet layers or the Jan 30 layer of facets, sun crusts, and isolated surface hoar beneath the recent snow.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 2