Avalanche Forecast
Issued: Apr 6th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Cornices.
astclair,
Avalanche Canada
Watch for cornices and reactive slabs in wind-drifted areas.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations.
Weather Forecast
Tuesday night: Overcast, scattered flurries with trace accumulations, moderate southwest wind, freezing level dropping to valley bottom.
Wednesday: Mix of sun and cloud with isolated light flurries, light west wind, treeline temperatures rising to -4 C, freezing level rising to 800 m and dropping to valley bottom overnight.
Thursday: Increasing cloud, flurries arriving late in the day, southwest wind increasing to strong, treeline temperatures rising to -3 C, freezing level rising to 700 m and dropping to valley bottom overnight.
Friday: Mix of sun and cloud, scattered flurries with up to 5 cm of accumulation, southwest wind decreasing to light, treeline temperatures rising to -2 C, freezing level rising to 800 m and dropping to valley bottom overnight.
Avalanche Summary
Strong winds contributed to intense wind-loading in areas over the weekend. Operators reported large (up to size 2) wind slab avalanches failing in immediate lee features and several natural cornice failures (up to size 2).
Reports from the weekend also included natural wet loose avalanches on south-facing slopes (up to size 2).Â
Snowpack Summary
Wind slabs formed by light amounts of recent snow and southwesterly winds may linger near ridgetops. Snow surface conditions include widespread wind-affect and a crust on steep south-facing slopes and at lower elevations. Cornices are large and looming at this time of year. Check out these reports from over the weekend from Hankin and Eliot Peak that illustrate the widespread wind-affect and large cornices.
Buried 70-120 cm deep, a spotty layer of surface hoar may exist on sheltered north aspects, but no recent avalanches have been reported on this layer.Â
The lower snowpack is reported as well settled and strong in most areas. However, weak facets exist at the base of the snowpack in the more shallow snowpack zones across the region. Where it exists, this layer has the potential to be triggered on steep, rocky slopes with a shallow or thin to thick snowpack; especially with large loads such as a cornice fall.
Terrain and Travel
- Be careful as you transition into wind affected terrain.
- Carefully evaluate steep lines for wind slabs.
- Avoid exposure to slopes that have cornices overhead.
Problems
Wind Slabs
Ongoing southwest wind and incremental flurries may combine with previous accumulations that fell over the weekend to form wind slabs in lee features that may be possible to trigger. Use caution around ridges and lee features and when transitioning into wind affected terrain.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Cornices
Cornices are large and looming along many ridgelines and have likely grown with the recent wind.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 7th, 2021 4:00PM
