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Avalanche Forecast

Archived

Jan 12th, 2023–Jan 13th, 2023

Alpine
Natural and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

North Columbia, South Columbia, Blue River, Premier, Grohman, Clemina, Esplanade, Jordan, North Monashee, North Selkirk, Shuswap, Badshot-Battle, Central Selkirk, Goat, Gold, Kokanee, North Okanagan, Retallack, Valhalla, Whatshan.

Avoid avalanche terrain. The incoming weather will increase the likelihood of human and naturally triggered avalanches.

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

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Persistent Slabs

Persistent Slab avalanches are the release of a cohesive layer of snow (a slab) in the middle to upper snowpack, when the bond to an underlying persistent weak layer breaks. Persistent layers include: surface hoar, depth hoar, near-surface facets, or faceted snow. Persistent weak layers can continue to produce avalanches for days, weeks or even months, making them especially dangerous and tricky. As additional snow and wind events build a thicker slab on top of the persistent weak layer, this avalanche problem may develop into a Deep Persistent Slab.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.