Avalanche Forecast
Issued: Jan 12th, 2023 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.
trettie,
Avalanche Canada
Avoid avalanche terrain. The incoming weather will increase the likelihood of human and naturally triggered avalanches.
Summary
Confidence
Moderate
Avalanche Summary
There are multiple layers in the top 1.5m of the snowpack that can and have produced rider triggered avalanches this week. Most avalanche activity has taken place at treeline but these layers have produced avalanches at all elevations.
Due to the shallow and weak nature of the snowpack it likely won't take as much input from the weather to increase the likelihood of human triggering.
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.
Snowpack Summary
A new crust can be found under 5 to 10cm of new snow on steep south facing terrain and low elevation terrain. Wind slabs exist on North, west and east facing terrain at treeline and above. Moist snow will be found below treeline as due to high freezing levels and rain.
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
Thursday Night
Stormy with 5 to 15cm of new snow at treeline and above, rain at lower elevations. Moderate to strong southerly winds and freezing levels around 1400m.
Friday
Stormy with up to 20cm of new snow expected at treeline and above. Rain at lower elevations. Freezing levels rising to 1900m. Moderate to strong southerly winds.
Saturday
Stormy with around 5cm of new snow expected at treeline and above. Light to moderate southerly winds. Freezing level around 1800m.
Sunday
Cloudy with flurries bringing trace amounts of new snow. Light southerly winds and freezing levels around 1400m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Storm slabs in motion may step down to deeply buried weak layers resulting in very large avalanches.
- Be especially cautious as you transition into wind affected terrain.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
Problems
Storm Slabs
New storm slabs will build throughout the day. The largest will likely be in the Monashees. Larger and more reactive slabs could be found on north and east aspects due to south/southwest winds.
There is a likelihood of storm slab avalanches stepping down to deeper layers.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
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
Valid until: Jan 13th, 2023 4:00PM
