Avalanche Forecast
Issued: Feb 1st, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
mconlan,
Avalanche Canada
Recently formed slabs will require some time to bond to the snowpack, particularly where they overly a widespread weak layer.
Summary
Confidence
Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.
Weather Forecast
TUESDAY NIGHT: Clear skies with no precipitation, 10 to 20 km/h north wind, alpine temperature -22 C.
WEDNESDAY: Increasing clouds with afternoon snowfall, accumulation 1 to 3 cm, 20 km/h southwest wind, alpine temperature -20 C.
THURSDAY: Cloudy with snowfall, accumulation 5 to 10 cm, 20 to 40 km/h west wind, alpine temperature -12 C.
FRIDAY: Cloudy with snowfall, accumulation 10 to 20 cm, 40 to 60 km/h southwest wind, alpine temperature -7 C.
Avalanche Summary
Widespread avalanche activity was observed on Monday. They were mostly small to large (size 1 to 2.5) storm slabs, being triggered naturally, by riders, and explosives. They often failed on the surface hoar crystals described in the snowpack summary. For areas where the recent snow had not formed a cohesive slab, small loose dry avalanches were observed.Â
A large explosive triggered the December 1 facet/crust layer described in the snowpack summary. The avalanche was at 1600 m in an opening, on a southwest aspect. It varied from 50 to 180 cm deep.
Looking ahead to the coming days, storm slab avalanches are expected to remain triggerable by riders as the recent snow settles and forms a cohesive slab above the widespread surface hoar layer.
Snowpack Summary
Around 30 to 60 cm of recent snow overlies weak surface hoar crystals 5 to 15 mm in size, which is most prominent in areas sheltered from the wind. The snow has consolidated and formed storm slabs in some areas, which is expected to remain touchy to riders for some time. In other areas, the snow remains uncohesive without slab properties. The snow overlies a melt-freeze crust on sun-exposed slopes. Expect to find wind slabs in lee terrain features at higher elevations.
A few other weak layers of surface hoar and faceted grains exist in the top metre of snow but are reported as hard to find.
The facet/crust layer that formed in early December is buried around 120 to 250 cm. The last reported avalanche was on January 31 from a large explosive, and before that on January 23. This is a low probability but high consequence problem. Check out the forecaster blog for more information.
Terrain and Travel
- Good day to make conservative terrain choices.
- Make observations and assess conditions continually as you travel.
- Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
Problems
Storm Slabs
Storm and wind slabs have formed from 30 to 60 cm of recent snow, which will remain touchy to riders for some time. The snow sits on a widespread layer of surface hoar crystals in areas sheltered from the wind and a hard crust on sun-exposed slopes. Expect to find wind slabs in steep terrain features at high elevations.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
A weak layer of faceted grains above a hard melt-freeze crust is buried around 120 to 250 cm deep. Although the likelihood of triggering this layer is expected to reduce given the current weather trend, the snowpack structure remains. Any release on this layer would be highly consequential.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 2nd, 2022 4:00PM
