Avalanche Forecast
Issued: Mar 6th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Cornices and Deep Persistent Slabs.
zryan,
Avalanche Canada
Don't let good visibility lure you into dangerous terrain. Wind slabs may exist on a variety of aspects due to recently shifting wind direction. The air is cold but the March sun can be strong so avoid exposure to cornices and watch for signs of warming on steep south aspects.
Recent observations suggest the deep persistent slab problem has been active in recent days. Keep this in mind as travel through terrain, especially in shallow snowpack areas in the north and east of the region.
Summary
Confidence
Moderate
Avalanche Summary
In the past few days, several natural and human-triggered wind slabs have been observed from a variety of aspects in alpine terrain and treeline terrain as northerly winds impacted the region. Check out this MIN from Pine Pass on Saturday for an example.
Another MIN report from Pine Pass on Sunday shows a very large deep persistent slab from alpine terrain that was likely triggered by a cornice failure or wind-loading. This is the first observation in several weeks of deep persistent slab activity and is an indication that this layer should be on our radar, particularly in the shallower snowpack areas in the region.
Snowpack Summary
Shifting winds have redistributed recent storm snow into wind slabs on a variety of aspects while soft snow remains in sheltered areas. Storm snow overlies heavily wind-affected snow.
The middle of the snowpack is generally strong.
A weak layer of large and weak facets is found near the base of the snowpack. This layer is of greatest concern in shallow snowpack areas in the north and east of the region.
Weather Summary
Monday night
Clear with cloudy periods. Alpine temperatures drop to a low of -10 °C. Ridge wind southeast 10-25 km/h. Freezing level at valley bottom.
Tuesday
A mix of sun and cloud with flurries. Alpine temperatures reach a high of -12 °C. Ridge wind south 25-40 km/h. Freezing level at valley bottom.
Wednesday
Sun and cloud with isolated flurries. Alpine temperatures reach a high of -13 °C. Ridge wind southeast 30-50 km/h. Freezing level at valley bottom.
Thursday
Sunny. Alpine temperatures reach a high of -6 °C. Ridge wind light from the southeast. Freezing level at valley bottom.
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.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- 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.
Problems
Wind Slabs
Variable winds over the past week mean that wind slabs could be found on all aspects.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Minimize your exposure to cornices, they have grown significantly in recent weeks and can trigger large avalanches on the slopes below. Give them respect and a wide birth when you are travelling under them. Be cautious of solar input.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
A weak layer of facets exists near the base of the snowpack. 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 7th, 2023 4:00PM
