Avalanche Forecast
Issued: Jan 1st, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Persistent Slabs and Deep Persistent Slabs.
mconlan,
Avalanche Canada
A stormy period is forecast for the weekend, increasing avalanche danger. Conservative terrain travel is needed during this time, with avoidance of avalanche terrain during periods of rapid snow accumulation or with signs of instability.
Summary
Confidence
Weather Forecast
FRIDAY NIGHT: Cloudy with snowfall, accumulation 5 to 10 cm, 60 km/h southwest wind, alpine temperature -6 C.
SATURDAY: Cloudy with snowfall, accumulation 10 to 15 cm, 70 km/h southwest wind, alpine temperature -5 C, freezing level 1000 m.
SUNDAY: Cloudy with snowfall, accumulation 10 to 20 cm, 60 km/h southwest wind, alpine temperature -7 C.
MONDAY: Cloudy with snowfall, accumulation 5 cm, 40 km/h south wind, alpine temperature -8 C.
Avalanche Summary
Avalanche activity is expected to spike during this stormy period, as slabs form and sufficient snow loads the buried weak layers described in the snowpack summary. Avalanches could be triggered naturally or by riders and the result may be very destructive.
Snowpack Summary
Around 20 cm of snow has accumulated in much of the region so far and the snow is forecast to continue to fall over the weekend. Storm totals could reach 40 cm by Saturday afternoon. Storm and wind slabs are likely forming rapidly and they may overly a weak and feathery surface hoar layer, particularly in sheltered treeline and below treeline terrain.
Around 50 to 100 cm deep, a hard melt-freeze crust from early December may have weak and sugary faceted grains around it. The last reported avalanche activity on this layer was around December 21. The likelihood of triggering this layer is expected to increase during this stormy period.
The early-November melt-freeze crust may be found near the base of the snowpack and may have weak faceted grains around it. The last reported avalanche activity on this layer was near Smithers on December 22. The most likely terrain to trigger it would be in shallow and rocky alpine areas.
Terrain and Travel
- Watch for fresh storm slabs building throughout the day.
- Avoid all avalanche terrain during periods of heavy loading from new snow and wind.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
Storm Slabs
We are in the midst of a stormy period that will build slabs at all elevations. The snow may be reactive in sheltered terrain where it could overly a weak layer of surface hoar. Strong wind from the southwest wind will create thick and touchy deposits in lee terrain features at higher elevations.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A weak layer may exist around 50 to 100 cm deep, composed of weak and sugary faceted grains above a hard melt-freeze crust. It has been over a week since the last reported avalanche on this layer, but the likelihood of triggering it may increase during this stormy period.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
The base of the snowpack has been reported as being composed of weak and sugary faceted grains for much of the region. The most likely area to trigger it would be on slopes where the snowpack is thin, such as near rocky outcrops.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 2nd, 2021 4:00PM
