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Avalanche Forecast

Archived

Feb 8th, 2022–Feb 9th, 2022

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

Regions

South Coast Inland.

The snowpack isn't a fan of rapid change. Freezing levels jumping 2000 m in a couple of hours on Wednesday is about as rapid as it gets. Hazard from wet loose slides might be the obvious problem, but an increasing likelihood of triggering a persistent slab is the most worrying.

Confidence

Moderate - Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.

Weather Forecast

Tuesday night: Cloudy with isolated flurries. Moderate to strong west or southwest winds. Freezing levels remaining near 1300 metres.

Wednesday: A mix of sun and cloud. Light to moderate west winds. Treeline high temperatures around +2 with freezing levels rising to 3300 metres.

Thursday: Sunny. Moderate to strong west winds. Treeline high temperatures around +1 with freezing levels remaining near 3000 metres, falling overnight.

Friday: Sunny. Light north winds. Treeline high temperatures around +1 with freezing levels rising from surface to 2500 metres.

Avalanche Summary

On Saturday a fatal avalanche occurred in the Duffey Lake area. This avalanche was a very large (size 3), skier triggered avalanche with significant propagation. It was triggered at upper treeline on a northeast aspect and it failed on a shallower layer of surface hoar before stepping down to the crust from late January discussed in our snowpack summary. A more detailed report can be found here. This layer was also responsible for several large skier triggered avalanches in the neighbouring Sea to Sky region.

We anticipate a significant increase in the likelihood of avalanches on this layer during the warming pattern from Wednesday onward.

Snowpack Summary

Another bout of strong southwest wind over Sunday night may have formed new wind slab on leeward aspects at treeline and above. Slab formation was likely hampered to a degree by already extensive recent wind redistribution as well as the recent formation of surface crusts at lower elevations and on solar aspects.

The primary concern in the snowpack at present is the 20 to 70 cm of snow from the past week that is sitting above a variety of surfaces including facets and crust, but also surface hoar in more sheltered areas at mid-elevations. This layer is most prominent at treeline and above. It has been found on all aspects in the Duffey Lake area. This layer is up to about 90 cm deep in the south of the region and has been giving similar, moderate to hard, sudden results in recent snowpack tests.

Terrain and Travel

  • Be aware of the potential for large avalanches due to the presence of buried weak layers.
  • Remote triggering is a concern, avoid terrain where triggering slopes from below is possible
  • If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.
  • Minimize overhead exposure; avalanches triggered by warming or cornice fall may be large and destructive.
  • Good day to make conservative terrain choices.

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.

Loose Wet

Loose Wet avalanches are the release of wet unconsolidated snow or slush. These avalanches typically occur within layers of wet snow near the surface of the snowpack, but they may quickly gouge into lower snowpack layers. Like Loose Dry Avalanches, they start at a point and entrain snow as they move downhill, forming a fan-shaped avalanche. Other names for loose-wet avalanches include point-release avalanches or sluffs. Loose Wet avalanches can trigger slab avalanches that break into deeper snow layers.

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.