Avalanche Forecast

Archived

Jan 10th, 2023–Jan 11th, 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 avalanches possible, human triggered probable.

Treeline

Natural avalanches possible, human triggered probable.

Below Treeline

Natural avalanches unlikely, human triggered possible.

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.

Continue to make conservative terrain choices and avoid shallow rocky slopes.

In General the snowpack is weak and there is an ongoing risk of triggering a deep persistent slab.

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.

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.

Between the 1st and 5th of January, widespread avalanche activity was reported on persistent/deep persistent weak layers throughout the Columbias. These avalanches were naturally and human triggered, up to size 3 (very large) and failed on the weak layers described in the Snowpack Summary 70-200 cm deep. Avalanches occurred on all aspects, and mostly between 1800 and 2500 m in elevation. Check out these MIN reports from Joss Mountain, & North McCrea Mountain for an idea of the scale and features of concern.

Small slabs in wind loaded features have also been triggered by riders, which have the potential of stepping down to these deeper weak layers.

Snowpack Summary

20 to 30cm of recent snow sits over a new layer of surface hoar. Below this a well-settled upper snowpack exists. A new crust can be found at or near the surface on steep south facing terrain and low elevation terrain. Variable winds have formed wind slabs at upper elevations.

Several buried weak layers in the mid to lower snowpack continue to be a concern although avalanche activity appears to be tapering off:

A layer of crust, facets and/or surface hoar buried around Christmas sits 40-70 cm deep.
A layer of large and weak facets from mid November sits near the ground.

This year's snowpack is weaker than usual, as described in our Forecasters' blog.

Weather Summary

Tuesday Night

Cloudy with trace amounts of new snow expected. Light southerly winds and a low of -12 at 1800m.

Wednesday

Cloudy with light flurries bringing trace amounts of new snow. Light southerly winds increasing to moderate throughout the day and a high of -6 at 1800m.

Thursday

Stormy with up to 10cm of new snow expected. Strong southerly winds and a high of -4 at 1800m.

Friday

Stormy with up to 15cm of new snow expected at treeline and above. Rain at lower elevations. Freezing levels around 1600m. Moderate to strong southerly winds.

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.