Avalanche Forecast

Archived

Dec 7th, 2020–Dec 8th, 2020

Alpine

Natural avalanches unlikely.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely, human triggered possible.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Kootenay Boundary.

As a dusting of flurries and snow enters the region, consider avalanche hazard MODERATE in areas that accumulate over 10 cm.

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

MONDAY NIGHT: Cloudy with isolated flurries / Moderate, south ridgetop wind / alpine low temperature -6 / Alpine inversion

TUESDAY: Cloudy with isolated flurries, trace to 10 cm / Light to moderate, gusty southwest ridgetop wind / alpine high temperature -1 / Freezing level 1100 m, alpine inversion

WEDNESDAY: Cloudy with isolated flurries, 5 cm / Light, gusty southwest ridgetop wind / alpine high temperature -4 / Freezing level 1000 m

THURSDAY: Cloudy / Light, south ridgetop wind / alpine high temperature -6 / Freezing level valley bottom

Avalanche Summary

Other than a few small loose-wet avalanches from steep terrain on the last few sunny days, the last avalanche observations were Wednesday Nov 2 when warming likely triggered numerous wet loose avalanches from NE slopes above 2000 m.

Have you been out and about in the mountains? If so please submit to the Mountain Information Network (MIN). It doesn't have to be technical it can be as simple as a photo. Photos are especially helpful! Sending a big thank you to the already submitted MIN's this season!

Snowpack Summary

Light flurries are expected to fly around the region. The snowpack surface consists of the recent melt-freeze crust on most slopes. Cold, dry snow and wind affected surfaces are found on more shaded aspects at around treeline and above. Additionally, surface hoar has been observed developing around the region. Snowpack depths vary with elevation, treeline averages between 50-100 cm.

Crusts from mid-and early-November are generally found 30 cm below the snow surface and 10 cm up from the ground at all elevations. While they are showing resistant planar results in snowpack tests, a lot of uncertainty still exists with limited observations and while we don't think they're currently a problem, we're not ready to throw them out yet.

Terrain and Travel

When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
Small avalanches can have serious consequences in extreme terrain. Carefully evaluate your line for wind slab hazard before you commit to it.

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.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.