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Avalanche Forecast

Archived

Feb 15th, 2022–Feb 16th, 2022

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

Regions

Kootenay Boundary.

Watch for fresh wind slabs around ridgelines from overnight westerly winds. 

Manage open slopes at treeline with caution, persistent slab avalanches are most likely here. Avalanches are unlikely where a thick surface crust exists.

Confidence

High - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.

Weather Forecast

TUESDAY NIGHT: Chance of flurries with moderate northwest winds. Partly cloudy with freezing levels dropping to valley bottom. 

WEDNESDAY: A mix of sun and cloud. Moderate northwest winds, freezing levels reach 1500m, alpine high of -2. 

THURSDAY: Increasing cloud. Strong northwest winds. Freezing levels rise toward 2000 m over the day. Alpine high of +2. 

FRIDAY: Mainly cloudy with isolated flurries. Strong northwest winds. Freezing levels remain around 2000 m. Alpine high +4.

Avalanche Summary

Loose dry sluffing has been reported within the new snow.

A size 1 skier accidental was reported on the late January surface hoar on Monday with limited details. Avalanche activity on this buried persistent weak layer increased last week, with size 1-3 slabs reported at treeline elevations. This layer is now below a thick melt freeze crust in most areas. 

Snowpack Summary

5-10cm of new snow overlies a variety of surfaces. Higher elevations have been heavily wind effected, and a melt freeze crust exists on solar aspects into the alpine. Lower elevations hold a widespread thick melt freeze on all aspects, surface hoar sits above the crust in sheltered terrain features. 

The late January interface is buried 20-40 cm deep, and consists of a melt-freeze crust at lower elevations and on solar aspects extending into the alpine. Surface hoar sits above the crust in sheltered areas at treeline and below. This layer is still producing human triggered avalanches and propagation-likely test results. 

The mid January interface is buried 40-70 cm deep, and consists of a crust, facets, and surface hoar. The snowpack below is well consolidated, with the early December crust/facet persistent weak layer buried 100-200 cm deep. It is currently considered dormant. We expect this layer to become active later this season, check out the forecaster blog for more information.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Be aware of the potential for large avalanches due to the presence of buried weak layers.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.

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.

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.