Avalanche Forecast
Issued: Mar 9th, 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
Seek out sheltered and shaded terrain to avoid wind slabs and the effects of the sun.
Persistent slab avalanches are mostly likely to be triggered in steep, rocky, and wind-affected areas.
Summary
Confidence
Moderate
Avalanche Summary
Monday to Thursday saw periods of intense solar input. This caused several cornices to fail. These occurred in the alpine and the impact that some of them had on the slopes below, caused the slope below them to avalanche.
Helibombing on Monday was able to trigger the deep persistent slab, creating avalanches up to size 4. These were in the alpine and the layer that was released was typically 150 cm down.
Over the weekend, a few natural and skier-triggered wind slabs (size 1 to 2) were reported from south, southwest, and east-facing alpine terrain as northerly winds impacted the region. One large (size 2.5) deep persistent slab was triggered by a cornice failure in very steep north-facing alpine terrain.
Snowpack Summary
A sun crust can be found on steep south-facing aspects. Surface hoar growth has been reported in sheltered areas. Shifting winds have redistributed last week's storm snow into wind slabs on a variety of aspects. This storm snow sits over wind-affected surfaces and a thin sun crust on steep south-facing slopes.
The mid-snowpack is generally well-settled and strong.
The November facets are still prominent at the base of the snowpack. Although this layer is showing signs of rounding, there is a significant difference in resistance between it and the overlying snow. These facets are most pronounced in shallow rocky areas.
Weather Summary
Thursday Night
Mostly clear, no accumulation, winds east southeast 10 to 20 km/h, treeline temperatures -8 °C with freezing levels dropping to the valley bottom.
Friday
Mostly sunny with cloudy periods, trace accumulation late in the day, winds east 20 to 30 km/h, treeline temperatures around -9 °C with freezing levels possibly reaching 1000 m.
Saturday
Mostly cloudy, 2 cm accumulation, winds southeast 10 to 25 km/h, treeline temperatures around -10 °C.
Sunday
A mix of sun and cloud, 2 cm accumulation, winds south 20 km/h gusting to 45, treeline temperatures -10 to -5 °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.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Avalanche hazard may have improved, but be mindful that deep instabilities are still present.
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 smaller avalanches in motion or cornice failures have the potential to produce very large avalanches with 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 10th, 2023 4:00PM
