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Avalanche Forecast

Archived

Jan 28th, 2023–Jan 29th, 2023

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

Regions

Cariboos, North Rockies, Blue River, Clearwater, McBride, Premier, Quesnel, Sugarbowl, Clemina, North Monashee, McGregor, Renshaw, Robson.

This challenging snowpack continues to produce avalanches. Stick to low-angle terrain away from any overhead hazard.

Read more in the latest Forecaster Blog.

Confidence

Low

Avalanche Summary

Both natural and human-triggered persistent and deep persistent slab avalanches continue to be reported daily. On Friday east of Prince George, skiers triggered a size 2 deep persistent avalanche on a northeast slope at 1700m, the avalanche was triggered from the shallowest portion of the feature and the crown depth varied from 30 cm to 1 m. Additionally, two very large (size 2.5-3) natural wind slabs were reported on northeast-east and southeast aspects around 1900 m.

On Thursday a few very large (size 2.5-3) natural wind slab avalanches were reported around 1800-2000 m. Additional ongoing evidence of weak basal facets continued with a size 3 deep persistent avalanche reported on a steep southeast slope at 2400 m.

On Monday, a fatal skier-triggered avalanche incident occurred in the Selkirk range near Revelstoke. The avalanche occurred on an east aspect at 1900 m, on a steep, open and unsupported slope. The size 2 avalanche had a crown depth of 50 cm and failed on surface hoar buried in early January.

Last weekend (Saturday), a fatal avalanche incident occurred in the Oasis riding area south of Valemont. This avalanche resulted in a rider fatality. This was a remotely triggered (from a distance) size 2.5 deep persistent slab avalanche on a north-northwest aspect at 2100 m. More details can be found here.

Avalanches like these are most likely to be triggered on steep, shallow and previously undisturbed slopes. Your best defence at this time is to stay diligent in choosing low-consequence terrain that has been heavily trafficked throughout the winter. Stay disciplined and adjust your expectation for this winter.

Snowpack Summary

20-40 cm recent snowfall covered a layer of surface hoar and thin crust on solar aspects at treeline and higher, and a supportive crust up to 1800 m. North and westerly winds have redistributed loose snow to lee terrain.

A prominent layer of buried surface hoar can be found roughly 40-70 cm deep. It is found in some places but not in others, and has been recently reactive to human triggering. The bottom of the snowpack is made up of large weak facets buried in late November, causing the Deep Persistent Slab problem for this region.

Weather Summary

Saturday night

Clear and with gusty ridgetop winds. Ridge wind northwest reaching 30 km/hr. Alpine temperature -24 C.

Sunday

Sunny in the morning with increasing clouds throughout the day. Ridge wind northwest 15-30 km/hr. Alpine temperature -20 C.

Monday

Sun and increasing cloud. Ridge wind southwest 15-30 km/hr. Alpine temperature rising to -16 C.

Tuesday

Flurries, 5-10 cm. Increasing southwest ridge wind 30-40 km/hr. Alpine temperatures rising to -12 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.
  • Approach lee and cross-loaded slopes with caution.
  • Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.

Problems

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.

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.