Avalanche Forecast
Issued: Dec 27th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
trettie,
Avalanche Canada
Continually assess the bond between the recent snow and the faceted surface below. Wind and storm slabs likely won't bond well meaning that they will remain reactive to rider traffic.
Summary
Confidence
Avalanche Summary
Over the past few days natural storm slab avalanches up to size 2.5 have been observed in the region. These storm slabs are generally failing on the layer of facets and surface hoar created during the cold snap.
Snowpack Summary
New wind slabs exist in exposed terrain at treeline and above with the largest being on west aspects. A new crust could be found on the surface at lower elevation terrain an on some sun exposed slopes.
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
Tuesday Night
Light flurries bringing trace amounts of new snow. Light southwest winds and a low of -6 at 1500m.
Wednesday
Mainly cloudy with light flurries bringing trace amounts of new snow. Light variable winds and a high of -5 at 1500m.
Thursday
Cloudy with light flurries bringing 5 to 10cm of new snow. Light northeast winds and a high of -6 at 1500m.
Friday
Cloudy with flurries bringing around 5cm of new snow. Light southwest winds and a high of -6 at 1500m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
Problems
Storm Slabs
The recent storm snow sits over a weak layer that formed during the recent period of very cold temperatures and is expected to remain reactive to human triggering, especially in wind-loaded terrain. The largest and most reactive storm slabs will likely be found on westerly aspects.
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 storm 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 28th, 2022 4:00PM
