Avalanche Forecast

Archived

Dec 22nd, 2023–Dec 23rd, 2023

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.

Below Treeline

Natural avalanches unlikely.

Alpine

Natural avalanches unlikely.

Treeline

Natural avalanches unlikely.

Below Treeline

Natural avalanches unlikely.

Regions

Kootenay Boundary, Bonnington, Grohman, Kootenay Pass, Norns, Rossland, South Okanagan, Ymir, Crawford, Moyie, St. Mary, Kokanee, Retallack, Valhalla.

6:30 AM Update: New snow and wind may form wind slabs. Use caution in lee terrain features.

Confidence

High

Avalanche Summary

A few small loose wet avalanches were naturally triggered on steep slopes Thursday. No recent persistent slab avalanche activity has been reported in the last week. If you go out in the backcountry, please consider sharing your observations on the Mountain Information Network (MIN).

Snowpack Summary

In sheltered locations at higher elevations, 10-20 cm of settled snow overlies a surface hoar layer. Surface snow is moist from 1900 m and below where a breakable crust is present near the surface. A prominent rain crust is found 40 to 70 cm deep, which is strong enough to cap another preserved layer of surface hoar found in most areas. Professionals are reporting that this weak layer is either decomposing or gaining strength, as there have not been significant results on this layer during tests recently. Typical snowpack depths at treeline are 70 to 110 cm, and taper rapidly below treeline.

Weather Summary

Friday Night

Cloudy with 5 to 15 cm of snow, alpine wind northwest 40 to 60 km/h, treeline temperature -6° C, freezing level dropping to valley bottom.

Saturday

Mix of sun and clouds with no precipitation, alpine wind northwest 30 to 40 km/h, treeline temperature -8° C.

Sunday

Cloudy with sunny periods with no precipitation, alpine wind west 20 to 30 km/h, treeline temperature -6° C.

Monday

Cloudy with sunny periods with no precipitation, alpine wind southwest 20 to 30 km/h, treeline temperature -7° C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Carefully evaluate bigger terrain features on an individual basis before committing to them.
Early season avalanches at any elevation have the potential to be particularly dangerous due to obstacles that are exposed or just below the surface.

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.