Avalanche Forecast
Issued: Dec 29th, 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
Use extra caution at treeline where persistent weak layers have been most reactive. Be aware that wind slabs could step down to deeper layers.
Summary
Confidence
Avalanche Summary
On Wednesday one size 1.5 avalanche was remotely triggered by a snowcat. This avalanche was at treeline on a northeast aspect and failed on the facets formed during last weeks cold period. In the north of the region explosives triggered several small wind slab avalanches.
Snowpack Summary
New wind slabs exist in exposed terrain at treeline and above on all aspects. A new crust exists on the surface below 1000m.
30 to 50cm of recent storm snow overlies a variety of surfaces formed during the previous cold snap. In the alpine these surfaces are generally facets, old wind slab and Surface hoar. At treeline it is more likely to find surface hoar at this interface in sheltered terrain.
A layer of surface hoar and facets from early December can be found down 50cm in shallower snowpacks and over 80cm in deeper areas. recently this layer has not been reactive but still produces sudden results in snowpack tests.
The mid November crust is buried down over a meter in most places and is unreactive. The mid and lower snowpack is generally well settled.
Weather Summary
Thursday Night
Cloudy with light flurries bringing around 5cm of new snow. Light southerly winds and a low of -5 at 1500m.
Friday
Cloudy with flurries bringing trace amounts of new snow. Light variable winds in the alpine and moderate northerly at valley bottom. High of -3 at 1500m.
Saturday
Cloudy with light flurries bringing trace amounts of new snow. Light southwest winds and a high of -4 at 1500m.
Sunday
Cloudy with no new snow expected. Light to moderate south winds and a high of -3 at 1500m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Use ridges or ribs to avoid areas of wind loaded snow.
Problems
Persistent Slabs
There are 2 persistent weak layers in the top meter of the snowpack. The first is a layer of facets formed during the period of arctic air and buried on December 22nd. This Surface hoar could also be found at this interface in sheltered treeline features.
The second is a layer of facets and surface hoar from early December. This layer could be buried as deep as 1 meter.
Both these layers are most concerning in sheltered treeline features where surface hoar is more likely to be present.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
winds have been variable over the past few days. wind slab could be found on all aspects at treeline and above.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 30th, 2022 4:00PM
