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 Persistent Slabs, Wind Slabs and Deep Persistent Slabs.
rgoddard,
Avalanche Canada
Wind slabs are developing at higher elevations
Large to very large avalanches continue to be produced from our complex snowpack.
Seek out low-angle terrain that has a deep snowpack to find the best and safest riding.
Summary
Confidence
Moderate
Avalanche Summary
Avalanche control work done on Friday produced very large (up to size 3.5) avalanches. These were from our persistent problem and deep persistent problem. Although fewer in number, Saturday's avalanches were of similar nature.
Under the right circumstances, riders can trigger these layers. Heavier loads like those created by smaller avalanches will trigger these deeper layers as well.
Snowpack Summary
At higher elevations, wind slabs are beginning to form from west and southwest winds. In sheltered areas surface hoar growth has been reported. The top 30 to 50 cm of snow contains a wide variety of layers that include, crusts, surface hoar, and facets. These layers have not yet produced widespread avalanches however, they are important to keep in mind as they vary with aspect and elevation as they still pose a hazard depending on your terrain choices.
Layers that are presently a concern include a surface hoar layer developed in early January and a melt-freeze crust from late December that is now down approximately 70 cm. These layers have created our persistent slab problem. The deep persistent slab problem stems from a weak layer created in mid-November and it is now buried 100 to 190 cm deep. These layers are a major concern and if triggered they can result in large avalanches.
Thank you for inputting your snowpack observations in the MIN. For more information on the state of the snowpack, click HERE.
Weather Summary
Sunday Night
Cloudy but clearing into the night, possible trace accumulation, 20 to 30 km/h west winds, treeline temperatures around -10 and -5 C.
Monday
Mostly cloudy with some sunny periods, trace accumulation, 20 to 35 km/h west winds, treeline temperatures around -5 C.
Tuesday
Cloudy with sunny periods, possible trace accumulation, 25 km/h northwest wind, treeline temperatures -7 C.
Wednesday
Mostly cloudy, no accumulation, 30 km/h northwest wind, treeline temperatures -4 C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
Problems
Persistent Slabs
A persistent weak layer of surface hoar responsible for many recent avalanches exists 50 to 70 cm deep in the snowpack. This depth is prime for human triggering. Below treeline this surface hoar may be replaced with a rain crust.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Shifting winds have been acting on 10 to 15 cm of loose snow sitting on a freezing rain or rime crust, likely forming small wind slabs on a wide range of aspects in exposed areas. Southwest winds has and will continue to be the primary factor here.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Weak, faceted grains make up the basal snowpack. A melt freeze crust may make this layer resistant to human triggering but where this crust is thin or absent than large destructive avalanches may occur. Be especially suspicious of shallow, rocky, or cross-loaded areas with variable snow depths.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 23rd, 2023 4:00PM
