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Avalanche Forecast

Archived

Feb 17th, 2022–Feb 18th, 2022

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

Regions

Kootenay Boundary.

Heightened avalanche conditions exist on open convex slopes. Avalanches are less likely where thick crusts exist near the surface.

Confidence

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

Weather Forecast

THURSDAY NIGHT: Cloudy skies, no significant precipitation, moderate wind from the northwest, treeline temperatures around -5 C.

FRIDAY: Cloudy skies, no significant precipitation, moderate wind from the west, treeline temperatures around -4 C with freezing level around 1200 m.

SATURDAY: Cloudy with flurries bringing 5-15 cm of snow by the evening, moderate wind from the southwest, treeline temperatures around -6 C.

SUNDAY: Another 5-10 cm of snow by the morning then clearing throughout the day with a mix of sun and cloud, light wind from the northwest, treeline temperatures drop from -5 to -10 C throughout the day.

Avalanche Summary

Most avalanche activity over the past few days has been small (size 1) human-triggered wind slabs along ridgetops and some small dry loose avalanches. Last week there were several large (size 2-3) persistent slab avalanches reported on the late January surface hoar layer, and this layer produced a few smaller (size 1) human-triggered slabs as recently as Tuesday.

Snowpack Summary

5 to 10 cm of fresh snow sits above hard wind-affect snow and melt-freeze crusts in most terrain. The exception could be north-facing terrain at treeline where there may still be soft snow. There are two layers of buried surface hoar in the upper snowpack: one was buried at the end of January and is 20 to 40 cm deep, the other was buried in the middle of January and is 30 to 50 cm deep. These layers remain reactive in some snowpack tests and resulted in avalanche activity over the past week. Triggering avalanches on this layer has become less likely in the past few days, but may still be possible on sheltered northerly slopes. The lower snowpack is well consolidated, with a crust/facet layer found 100 to 200 cm deep. This layer is currently considered dormant, but could become active later this season as discussed in this forecaster blog.

Terrain and Travel

  • Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
  • Pay attention to isolated alpine features as well as cross-loaded features at treeline.
  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.

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.