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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

Sea To Sky.

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 diminishing flurries and a final trace of new snow. Moderate west winds, potentially strong in the alpine. Freezing levels remaining near 1300 metres.

Wednesday: Diminishing cloud, possibly remaining overcast. Light to moderate west winds. Treeline high temperatures around +2 with freezing levels rising to 2700m.

Thursday: Sunny. Light to moderate northwest winds, potentially strong in the alpine. Treeline high temperatures around +1 with freezing levels remaining around 2700 metres.

Friday: Sunny. Light variable winds. Treeline high temperatures around +1 with freezing levels between 2200-2700 metres.

Avalanche Summary

On Saturday in the South Coast Inland region a fatal size 3 (very large) skier triggered avalanche was reported in the Duffey Lake area. It ran on the persistent weak layer from late January described in our snowpack summary. This avalanche was triggered in a upper treeline feature on a northeast aspect and showed significant propagation. Click here to read a more detailed report. 

This is the same layer that was responsible for a skier triggered size 2.5 avalanche last week on Rainbow mountain. Several smaller skier triggered avalanches on this layer were also reported throughout the week. Most of the avalanche activity on this layer has taken place between 1800m and 2000m but it can be found above and below this elevation band. 

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

Snowpack Summary

Tuesday's flurries should bring 5-10 cm of new snow to the surface by Wednesday morning, burying heavy wind effect and recent wind slab formations resulting from recent south winds that reached up to 120 km/h on Monday morning. The new snow will bury surface crusts at lower elevations and on solar aspects.

Our problematic January layer of facets on crust is now buried down 30 to 70 cm. This layer is widespread between 1800 m and 2000 m, but may be found just above or below this elevation band. It has produced several human and remote triggered avalanches in the past few days. In sheltered terrain at treeline and above, surface hoar may also be found on this layer and it will certainly promote slab reactivity where it exists.

Terrain and Travel

  • Be aware of the potential for large avalanches due to the presence of buried weak layers.
  • Remote triggering is a concern, watch out for adjacent and overhead slopes.
  • 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.