Avalanche Forecast
Issued: Jan 9th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
MBender,
Avalanche Canada
It may be tempting to get into bigger terrain, however high consequence persistent slab avalanches continue to be reported every few days. The best and safest riding will be found in mellow wind sheltered terrain.
Summary
Confidence
Weather Forecast
Saturday Night: Flurries, accumulation 5-10 cm, moderate southwest wind, alpine high -5, freezing level 700 m.
Sunday: Mainly cloudy with flurries, accumulation 5-10 cm, moderate southwest wind, alpine high -3, freezing level 900 m.
Monday: Snow, accumulation 10-20 cm, moderate to strong southwest wind, alpine high -1, freezing level 1300 m.
Tuesday: Snow or rain, moderate to strong southerly wind, alpine high 0, freezing level 1600 m.
Avalanche Summary
Late Saturday there was a report of size 3 skier triggered avalanche at treeline on a westerly aspect on Cowboy Ridge. Details are limited at this time.
On Thursday there was a report of a remotely triggered (from a distance of 20m) size 2.5 deep persistent slab avalanche on a west aspect at 1930 m on Cowboy Ridge. The fracture line was up to 200 cm deep. This avalanche subsequently triggered an additional size 2.5-3 deep persistent avalanche about 50 m below.
On Wednesday there were numerous size 2 explosives controlled storm slab avalanches reported running in the alpine and treeline. As well there were several persistent and one deep persistent slab size 2.5-3 ranging in depth from 100-150 cm.
Snowpack Summary
Storm snow from the past week has seen extensive wind effect at upper elevations, with scoured windward aspects, wind slabs in lee features and growing cornices at ridgetop.
The snowpack is currently quite complex. The layer of greatest concern is a melt-freeze crust from early December, found around 100-200 cm deep in the snowpack. This crust may have surface hoar or sugary faceted grains sitting above it. There have been several recent large natural and human triggered avalanches on this layer and large loads have potential to trigger these layers. Near the base of the snowpack there are facets sitting on a crust from early November which have been identified as the failure layer in recent sporadic large avalanche releases.
Terrain and Travel
- Be careful as you transition into wind affected terrain.
- Make conservative terrain choices and avoid overhead hazard.
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Cornice failure may trigger large avalanches.
Problems
Wind Slabs
Recent strong to extreme southerly wind has created widespread wind effect. Expect to see deep wind deposits in exposed lee terrain.
Aspects: North, North East, South West, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A couple of problematic layers may be found around 100 to 200 cm deep, including weak layers of surface hoar and faceted grains above a hard melt-freeze crust. Sporadic avalanche activity on these layers this week means there is still potential for avalanches to step down to these layers.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 10th, 2021 4:00PM
