Avalanche Forecast
Issued: Jan 22nd, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Persistent Slabs and Deep Persistent Slabs.
rgoddard,
Avalanche Canada
Continue to use conservative terrain choices and have a 'plan B' to avoid getting surprised.
Be aware that weak layers buried further down in the snow pack are still a factor.
Summary
Confidence
Moderate
Avalanche Summary
Much of Saturday's avalanche activity was focused in West Purcell. These avalanches were caused by a mix of storm slab, wind slab, and cornice fall. They have been triggered accidentally and with the use of explosives.
An avalanche of note was a size 2 that a skier triggered accidentally. This avalanche was of note because it was from our persistent slab problem, buried surface hoar and because it happened on such a low angle. Our persistent slab problem and deep persistent slab problem are still problems.
Snowpack Summary
Surface hoar growth has developed into the alpine. Wind slabs can be found in exposed areas. The top 20 of snow may contain a surface hoar or rain crust layer depending on elevation and location within the region.
Buried layers that are presently a concern are as follows. The first is down 30 to 50 cm and is a layer of surface hoar from early January. The second is a layer of surface hoar, facets, and crust created in December and found 40 to 90 cm down. The surface hoar is most prevalent in sheltered areas while crusts and any associated faceted snow are more widespread.
The bottom of the snowpack contains yet more weak, faceted snow. The total depth of this weak and shallow snowpack ranges between 80 and 180 cm at treeline and can be found at its most shallow in the eastern part of our region.
Weather Summary
Sunday Night
Mostly clear, possible trace accumulation, 15 to 25 km/h west winds, treeline temperatures of -9 C.
Monday
A mix of sun and cloud, trace accumulation, 20 to 30 km/h west wind, treeline temperatures -10 to -6 C.
Tuesday
A mix of sun and cloud, no accumulation, 25 km/h west northwest wind, treeline temperatures -9 C.
Wednesday
Cloudy with sunny breaks, no accumulation, 20 to 30 km/h northwest wind, treeline temperatures -10 C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Problems
Wind Slabs
Shifting winds have been acting on 15 to 25 cm of recent snow, likely forming wind slabs on a wide range of aspects in exposed areas.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
There are two weak layers in the top meter of the snowpack that continue to produce human-triggered avalanches. The first is a layer of surface hoar down 30 to 40 cm buried in early January. The second is a layer of surface hoar, facets and/or a crust from December. This layer can be found down 40 to 70 cm.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
A weak layer near the base of the snowpack, buried in November, continues to produce large, destructive avalanches with heavy loads. Human triggering of this layer remains possible as well, especially in shallow areas with variable snow depths.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 23rd, 2023 4:00PM
