Avalanche Forecast

Archived

Jan 9th, 2023–Jan 10th, 2023

Alpine

Natural avalanches possible, human triggered probable.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely, human triggered possible.

Below Treeline

Natural avalanches unlikely.

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.

Avalanche conditions remain tricky and buried weak layers still triggerable.

Avoid rocky or wind affected terrain features where the snowpack varies from thick to thin, as weak layers can be more easily triggered. Check out the new Forecasters' Blog for more details on managing this season's challenging snowpack.

Confidence

Moderate

Avalanche Summary

We received a report of a serious incident involving two snowmobilers late Monday afternoon near Kaslo. The size 2.5 avalanche was human triggered on a west facing slope at treeline around 2100 m, failing on the deeply buried November facets.

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 and Western Purcells. 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

10-20 cm of new snow sits over a well-settled upper snowpack. A shallowly buried layer of small surface hoar, rime crust or sun crust may be found near the surface. Southerly winds have redistributed surface snow into leeward terrain features at upper elevations. Wind slabs may sit over the layer of surface hoar and/or crust.

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

Monday night

5-10 cm of new snow. Light to moderate southwest wind. Alpine low of -6 °C.

Tuesday

Cloudy with sunny breaks. Light southerly winds. Alpine highs of -2 °C.

Wednesday

A mix of sun and cloud. Light to moderate southerly winds. Alpine high of -3 °C.

Thursday

5-10 cm of new snow. Strong southerly winds. Alpine high of -1 °C.

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.