Avalanche Forecast
Issued: Dec 28th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
trettie,
Avalanche Canada
Continually assess the bond between the recent snow and the faceted surface below. Wind slabs likely won't bond well meaning that they will remain reactive to rider traffic.
Summary
Confidence
Moderate
Avalanche Summary
On Wednesday explosives triggered several wind slabs up to size 1.5. These avalanches were in steep north facing terrain.
Earlier in the week several natural storm and persistent slab avalanches occurd on a variety of aspects. This type of avalanche activity has tapered off but persistent weak layers in the snowpack will likely remain rider triggerable in specific terrain features at treeline.
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.
Around 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
Wednesday Night
Mainly cloudy with light flurries bringing trace amounts of new snow. Light easterly winds and a low of -5 at 1500m.
Thursday
Cloudy with light flurries bringing around 5cm of new snow. Light southerly winds and a high of -5 at 1500m.
Friday
Cloudy with flurries bringing around 5cm of new snow. Light southeast winds and a high of -3 at 1500m.
Saturday
Cloudy with light flurries bringing around 5cm of new snow. Light southerly winds and a high of -4 at 1500m.
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.
- Use ridges or ribs to avoid areas of wind loaded snow.
- 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.
Problems
Wind Slabs
winds have been variable over the past few days. wind slab could be found on all aspects at treeline and above. These wind slabs could overlie facets in the alpine and surface hoar as well as facets at treeline. Wind slab over facets or surface hoar will be larger and more reactive.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
There are two persistent weak layers in the mid and lower snowpack. The first is a layer of surface hoar and facets from early december. This layer is most concerning at treeline and continues to produce sudden results in snowpack tests. The second is a layer of facets and a crust from mid November. This layer has not shown reactivity recently.
Be aware that wind slab avalanches have the possibility to step down to these layers resulting in larger and more destructive avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 29th, 2022 4:00PM
