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Avalanche Forecast

Archived

Feb 3rd, 2022–Feb 4th, 2022

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

Regions

Kootenay Boundary.

Buried surface hoar may become touchy as snow accumulates. Approach steep open slopes at treeline and below with caution. Watch for signs of instability & consider conservative terrain as a way to manage uncertainty.

Wind slab will continue to form in exposed terrain.

Confidence

Moderate - Uncertainty is due to how the snowpack will react to the forecast weather. We are confident about the possible sizes of avalanches, should one release; what is less certain is the likelihood of triggering.

Weather Forecast

Light snowfall is forecast for Friday. Temperatures rise and skies clear for the weekend.

THURSDAY NIGHT: Mainly cloudy. Moderate westerly winds. Chance of flurries. Freezing level valley bottom. 

FRIDAY: Cloudy with 10-15 cm of low density snow and strong southwest winds. Alpine high of -7. Freezing levels around 500 m. 

SATURDAY: Strong west/northwest winds . Cloudy with a chance of flurries. Alpine high of -3, as freezing levels rise to 1000 m over the day. 

SUNDAY: Clearing skies, no precipitation expected. Alpine high of 0, with freezing levels rising to 2000 m with an inversion possible. Moderate westerly winds. 

Avalanche Summary

Human triggered slabs to size 2 have been reported each day this week, up to size 2 in wind loaded terrain features. Activity has mainly been at higher elevations, on north and east facing slopes. 

Several size 1 loose dry avalanches were also reported, mostly in steep terrain features. 

Snowpack Summary

At lower elevations up to 35cm of storm snow sits over a melt freeze crust. In sheltered terrain a widespread layer of large surface hoar crystals sits immediately above the crust, sensitive to human triggers.

At higher elevations the storm snow is being redistributed by moderate to strong westerly winds. A thin melt freeze crust extends into the alpine on solar aspects. This crust may sit on the surface in exposed terrain, or below wind deposited snow in sheltered features increasing reactivity. 

The upper snowpack then consists of several crusts and surface hoar layers, 30-70 cm deep. Recent reactivity has appeared limited to the storm snow and most recent surface hoar. 

The early December crust/facet persistent weak layer is buried down 100-200 cm and has been responsible for significant avalanche activity in this region. The layer is now considered dormant, but still remains a concern and we will continue to track it in the snowpack. See the most recent forecaster blog on how to manage this layer, as it will come into play again later this season. 

Terrain and Travel

  • Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
  • Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.

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.