Avalanche Forecast

Archived

Jan 11th, 2023–Jan 12th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

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.

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.

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.

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

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.

Wind Slabs

Wind Slab avalanches are the release of a cohesive layer of snow (a slab) formed by the wind. Wind typically transports snow from the upwind sides of terrain features and deposits snow on the downwind side. Wind slabs are often smooth and rounded and sometimes sound hollow, and can range from soft to hard. Wind 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.