Avalanche Forecast
Issued: Dec 22nd, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
trettie,
Avalanche Canada
carefully assess each slope for wind slab. wind slab avalanches have the potential to step down to deeper layers.
Summary
Confidence
Moderate
Avalanche Summary
On Tuesday and Wednesday several size one skier triggered wind slab avalanches were reported. These avalanches were on easterly aspects at upper treeline.
Snowpack Summary
Variable winds mean that wind slab could be found on all aspects at treeline and above. These new slabs will form over facets, surface hoar or a crust meaning they will not bond well.
The snow becomes slightly more consolidated after the above mentioned layer until around 50cm below the surface where another weak layer, created in early December, can be found. This layer is made up of surface hoar in sheltered areas and a thin sun crust in open south-facing terrain.
The layer that is still the main concern, is that of mid-November. It is made up of large surface hoar crystals, facets, and a melt-freeze crust and can be found up to 80 cm deep. This layer has been reactive at treeline between 1700 to 2200 m, on all aspects.
The snowpack is becoming increasingly complex and faceted.
Weather Summary
Thursday Night
flurries bringing up to 5cm of new snow. Light westerly winds and a low of -20 at 1800m.
Friday
Cloudy with up to 10cm of new snow expected. Westerly winds increasing throughout the day to strong . High of -15 at 1800m.
Saturday
Stormy with around 15cm of new snow expected. Strong southwest winds and a high of -6 at 1800m.
Sunday
Cloudy with trace amounts of new snow expected. Light to moderate westerly winds with a high of -6 at 1800m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
Problems
Persistent Slabs
There are three persistent weak layers within the snowpack.
The first is only recently just been buried , it is currently not a concern as the snow above has not formed a slab. It is a surface hoar layer in sheltered terrain and a crust on south facing slopes.
The second is a weak layer of surface hoar on shaded aspects and crust on steep solar aspects found down around 50cm.
The third is a layer of surface hoar and facets from mid-November which is buried down around 80cm in the region.
While avalanche activity has tapered off on these layers they likely remain rider triggerable in specific sheltered terrain features at treeline and below.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Variable winds mean that wind slab could be found on all aspects at treeline and above. These slabs will likely overlie facets, a crust or surface hoar meaning that they could be touchy. When strong winds are observed slabs could be found further down slope than expected.
Be aware that wind slab avalanches could step down to deeper layers.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 23rd, 2022 4:00PM
