Avalanche Forecast

Issued: Dec 3rd, 2022 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs and Persistent Slabs.

wlewis, Avalanche Canada

Purcells, Dogtooth, East Purcell.

Watch for lingering wind slab at higher elevations where winds have varied in direction. Small avalanches have the potential to trigger deeper weak layers. Assess conditions as you travel and gain information.

Summary

Confidence

Moderate

Avalanche Summary

Observations are currently very limited. A small slab avalanche was observed Thursday around 2000 m on a steep, south-facing road bank. It failed and propagated on the sugary, faceted layers snowpack, 25 cm deep.

We have very few eyes out there. If you do get out please consider reporting in the MIN.

Snowpack Summary

The upper snowpack has been redistributed by variable winds into wind slabs that can be found on many aspects, these overlie a generally weak, sugary, facetted lower snowpack. In exposed terrain slopes may have been scoured back significantly. A buried layer of surface hoar sits 25-45 cm deep and remains a layer of concern.

The overall height of snow is highly variable throughout the region with around 70-150 cm in the alpine.

Weather Summary

Saturday Night

Mostly clear skies overnight. Light to moderate westerly winds. No snowfall expected.

Sunday

Clear skies, light westerly winds. No snowfall expected. Alpine high of -12.

Monday

Mostly sunny with scattered cloud, moderate westerly winds and alpine temperatures around -15 C. No snowfall expected.

Tuesday

A mix of sun and cloud with isolated flurries bringing trace amounts. Moderate to strong westerly winds. Alpine high of -17.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

Expect slab conditions to change drastically as you move into wind exposed terrain.
Carefully evaluate steep lines for wind slabs.
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 slabs have formed behind ribs and ridges in the alpine and treeline. Avoid snow that feels drum like or hollow. In exposed areas extreme winds may strip the slopes - making for poor travel and riding conditions. These cohesive slabs likely overlay a weak, sugary lower snowpack

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

Buried layers of surface hoar and facets have been reportedly been reactive. It will be most reactive where the snow above these layers acts as a slab (as opposed to loose snow) such as wind loaded areas.

Observations on this layer are currently limited. In times of uncertainty such as this, the best defence is to keep terrain choices conservative and reduce your exposure to avalanche terrain where possible.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Dec 4th, 2022 4:00PM