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Avalanche Forecast

Archived

Dec 14th, 2021–Dec 15th, 2021

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

Regions

Kootenay Boundary.

Continually assess the wind effect as you move through terrain. Avoid slopes where slab properties exist above a persistent weak layer.

Confidence

Moderate -

Weather Forecast

Tuesday night: some light flurries bringing up to 5cm with light West winds. A low of -10 is expected for 1700m.

Wednesday: trace amounts of snow with light Southwest winds.High temperature at 1700m -6.

Thursday: Trace amounts of new snow with a high of -7 at 1700m. Winds becoming moderate from the Northwest. 

Friday: 5cm of new snow with moderate west winds and a high of -6 at 1700m.

Avalanche Summary

On Monday two natural wind slab avalanches up to size two were observed on a Northeast aspect at 2300m in the North part of the forecast region.

Snowpack Summary

Recent storm snow has been redistributed by Southeasterly winds, Look for new wind slab on reverse loaded features in upper elevations.

The defining feature of the snowpack is a prominent and widespread crust that now sits 30-70 cm below the surface. In many places, overlying snow is well-bonded to the crust but in others, including Kootenay Pass, weak faceted grains have been observed growing above it around treeline.  

Snow depths are roughly 140-180 cm at treeline throughout the region.

Terrain and Travel

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.

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.