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Avalanche Forecast

Archived

Feb 2nd, 2022–Feb 3rd, 2022

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 and human triggered avalanches likely.
Treeline
Natural and human triggered avalanches likely.
Below Treeline
Natural and human triggered avalanches likely.

Regions

North Columbia.

Diligence will be the name of the game for the foreseeable future. A widespread buried weak layer is at a prime depth for human triggering.

Confidence

High - We have a good understanding of the snowpack structure and confidence in the weather forecast

Weather Forecast

WEDNESDAY NIGHT: Cloudy with snowfall, accumulation 5 cm, 20 to 40 km/h southwest wind, alpine temperature -16 C.

THURSDAY: Cloudy with snowfall, accumulation 2 to 5 cm, 20 to 40 km/h west wind, alpine temperature -12 C.

FRIDAY: Cloudy with snowfall, accumulation 15 to 25 cm, 40 to 60 km/h southwest wind, alpine temperature -7 C.

SATURDAY: Cloudy with snowfall, accumulation 10 to 20 cm, 30 to 50 km/h west wind, alpine temperature -8 C, freezing level rising to 1300 m.

Avalanche Summary

Many storm and wind slabs were triggered by riders and explosives in the recent snow, with most releasing on the surface hoar layer described in the Snowpack Summary. They often occurred between 1700 and 2200 m on east, north, and west aspects.

Similar slabs are expected to be easily triggered by riders where the recent snow sits on surface hoar crystals. Stay diligent!

Snowpack Summary

Around 30 to 60 cm of recent snow overlies a weak lay of surface hoar crystals 5 to 15 mm in size, which is most prominent in areas sheltered from the wind. Example terrain features include the lee side of protected ridges, openings in the trees, cut blocks, and burns. The snow has consolidated and formed storm slabs in some areas, which is expected to remain touchy to riders for some time. In other areas, the snow remains non-cohesive without slab properties, but has the potential to switch at any time. The snow overlies a melt-freeze crust on sun-exposed slopes. Expect to find wind slabs that formed from variable wind directions at higher elevations.

The facet/crust layer that formed in early December is buried around 120 to 250 cm. The last reported avalanche was on January 31 from a large explosive, and before that on January 23. Although unlikely, the layer could be triggered from a large load like a cornice fall or a shallower slab avalanche could step down to this layer. Humans are unlikely to trigger it, with perhaps the exception in thin, shallow snowpack areas. Check out the forecaster blog for more information.

Terrain and Travel

  • Good day to make conservative terrain choices.
  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Shooting cracks, whumphs and recent avalanches are strong indicators of an unstable snowpack.
  • Make observations and assess conditions continually as you travel.
  • Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
  • Avoid shallow, rocky areas where the snowpack transitions from thick to thin.

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.

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.