Avalanche Forecast
Issued: Mar 8th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
rgoddard,
Avalanche Canada
Limit your exposure on solar slopes during the warmest part of the day.
Triggering large slab avalanches remains possible in steep, rocky, and wind-affected areas.
Sheltered and shaded terrain will offer the best and safest riding.
Summary
Confidence
Moderate
Avalanche Summary
Over the last couple of days, the sun has started to play a role in triggering natural avalanches. Wind slabs found on southwest to southeast aspects were released and reached up to size 2.5. Most of these were in the alpine and some at treeline.
In the southern part of our region, a wind slab was triggered by a skier accidentally. This triggered the deep persistent slab and created a size 2 avalanche. This was on a west aspect and in the alpine and where it was triggered was on a feature where the snowpack went from thick to thin. Another persistent slab avalanche was reported from the northern part of our region. It released naturally in the alpine and the layer that it failed on was 200 cm down in the snowpack.
Read more about managing the deep persistent slab problem in our latest Forecaster Blog.
Snowpack Summary
In the alpine and at treeline wind slabs may be found on all aspects due to variable winds. These wind slabs are made of the 20 to 60 cm storm snow that arrived last week. In areas not affected by the wind, this recent snow overlies a weak layer of faceted snow and a sun crust on sun-affected slopes.
This time of year the sun can really affect the snowpack. A sun crust should be expected on solar aspects. Moist snow could be found on the surface at lower elevations and during the heat of the day as well as on solar aspects.
The mid-snowpack is generally strong but the lower snowpack is a different story. The November facets are still prominent at the base of the snowpack. They are showing signs of rounding but there is still a considerable step in resistance between them and the overlying snow. These facets are most pronounced in shallow rocky areas.
Weather Summary
Wednesday Night
Clear, trace accumulation, winds easterly 20 km/h, treeline temperatures around -10 °C.
Thursday
Sunny with late-day clouds, no accumulation, winds easterly 10 to 20 km/h, treeline temperatures -8 °C.
Friday
Mostly cloudy, 5 to 8 cm focused mostly in the south, winds southerly 15 to 25 km/h, treeline temperatures -12 to -8 °C.
Saturday
A mix of sun and cloud, 5 to 10 cm accumulation mostly arriving in the early morning hours, winds southerly 20 to 25 km/h, treeline temperatures around -10 °C.
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 extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
Problems
Wind Slabs
Variable winds over the past week mean that wind slabs could be found on all aspects. Keep your guard up as you enter wind-affected terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
A weak layer of facets exists near the base of the snowpack. The likelihood of human triggering is low given the layer's depth, but large triggers such as cornice failures or smaller avalanches in motion have the potential to produce very large avalanches with surprisingly wide propagation. Suspect terrain for human triggering includes steep, shallow and rocky terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 9th, 2023 4:00PM
