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Avalanche Forecast

Archived

Jan 30th, 2023–Jan 31st, 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 avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural and human triggered avalanches likely.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.

Regions

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

Stormy conditions will increase the likelihood of triggering large, destructive avalanches over the coming days.

Confidence

Moderate

Avalanche Summary

On Sunday, many small to large (size 1 to 3) wind slab avalanches were triggered naturally and by riders, occurring on all aspects at treeline and alpine elevations. Various deep persistent slab avalanches were also triggered naturally, being large to very large (size 2 to 4). The avalanches occurred on all aspects between 2400 and 2800 m.

High-consequence avalanche activity is occurring daily, which is ongoing for several weeks now. Most of the avalanches over the past week released between 1800 and 2800 m, on all aspects. See here for information on a fatal skier-triggered avalanche incident from last week.

Your best defense is to stay diligent in choosing low-consequence terrain away from overhead exposure. Stay disciplined and adjust your expectation this winter. See more on the potential of triggering deeper weak layers Forecasters' Blog.

Snowpack Summary

New snow and westerly wind will form new wind slabs in lee terrain features. The new snow will overly previously wind affected snow in the alpine and a small layer of surface hoar crystals in wind-sheltered terrain.

A thick melt-freeze crust up to 1700 m around Revelstoke and 2000 m further south is buried about 20 to 50 cm deep. At this same depth, a small layer of surface hoar crystals may be found around treeline and lower alpine elevations in wind-sheltered terrain.

Two layers of surface hoar which formed in early January are 50 to 100 cm deep. These weak layers continue to be reactive to human triggering, although snowpack tests are starting to indicate they may be slowly strengthening.

Large and weak facets from November are near the base of the snowpack, which continue to produce very large avalanches in the region, as described in the Avalanche Summary.

Weather Summary

Monday Night

Cloudy with snowfall, accumulation 5 to 15 cm with local enhancements possible, 20 to 30 km/h west wind, treeline temperature -14 °C.

Tuesday

Cloudy with snowfall, accumulation 5 to 10 cm with local enhancements possible, 20 to 30 km/h west wind, treeline temperature -12 °C.

Wednesday

Cloudy with snowfall, accumulation 5 to 10 cm with local enhancements possible, 20 to 40 km/h southwest wind, treeline temperature -10 °C.

Thursday

Cloudy with snowfall, accumulation 5 to 15 cm, 30 to 40 km/h southwest wind, treeline temperature -5 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • 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.
  • Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.

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.

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.

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.