Avalanche Forecast
Issued: Jan 11th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Deep Persistent Slabs and Wind Slabs.
trettie,
Avalanche Canada
Make conservative terrain choices and think about the consequences of being wrong. Small avalanches can step down to deeper layers resulting in large and dangerous avalanches.
In General the snowpack is weak and there is an ongoing risk of triggering a deep persistent slab. Stay away from steep, shallow and rocky terrain features.
Summary
Confidence
Moderate
Avalanche Summary
We received a report of a serious incident involving two skiers late Monday afternoon near Kaslo. The size 3 avalanche was human triggered on a west facing slope at treeline around 2100 m, failing on the deeply buried November facets. This MIN report has more details.
Several size 2 skier triggered avalanches were reported on Tuesday. Most of this avalanche activity was on the surface hoar layer from January and were triggered at treeline on all aspects.
Although persistent/deep persistent slab avalanche activity has tapered off somewhat in recent days, reports continue to trickle in. Natural and human-triggered size 2s reported over the weekend show evidence that these layers are still reactive to human triggers and are capable of producing large avalanches.
Snowpack Summary
A new crust can be found at or near the surface on steep south facing terrain and low elevation terrain. Variable wind effect can be found in the upper treeline and alpine.
20 to 40cm of recent snow sits over a new layer of surface hoar from early January. Below this a well-settled upper snowpack exists.
Several buried weak layers in the mid to lower snowpack continue to be a concern although avalanche activity appears to be tapering off. The most concerning of these layers are A layer of crust, facets and/or surface hoar buried around Christmas down 40-75 cm and A layer of large and weak facets from mid November near the ground.
This year's snowpack is weaker than usual, as described in our Forecasters' blog.
Weather Summary
Wednesday Night
Cloudy with light flurries bringing trace amounts of new snow. Light to moderate southerly winds and a low of -7 at 1800m.
Thursday
Stormy with up to 10cm during the day and another 10cm of new snow in the evening at treeline and above. Moderate to strong southerly winds and freezing levels rising to 1500m.
Friday
Stormy with up to 25cm of new snow expected at treeline and above. Rain at lower elevations. Freezing levels around 1900m. Moderate to strong southerly winds.
Saturday
Stormy with around 10cm of new snow expected at treeline and above. Light to moderate southerly winds. Freezing level around 1800m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- Be especially cautious as you transition into wind affected terrain.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Problems
Persistent Slabs
Several concerning weak layers exist in the snowpack. The first is a layer of surface hoar buried in early January. The second is a layer of facets and a crust buried around Christmas, surface hoar may also be found at this interface.
Both these layers are most concerning at treeline but could produce avalanches at all elevations.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
A layer of large and weak facets sits near the base of the snowpack. This layer has most recently been problematic in lower alpine elevations.
Avoid thin and rocky start zones where weak layers sit closer to the surface, riders are most likely to trigger an avalanche on this layer in terrain with shallow or variable snow depths.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Wind slabs could be found on all aspects at treeline and above. As new snow arrives with southerly wind, the largest and most reactive wind slabs will be found on northerly aspects.
Avalanches triggered in wind-loaded terrain have the potential to step down to deeper weak layers, creating larger than expected avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 12th, 2023 4:00PM
