Avalanche Forecast

Issued: Jan 2nd, 2018 4:45PM

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

Avalanche Canada jfloyer, Avalanche Canada

Warming alpine temperatures may give some surprising releases, especially in steep terrain.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

Wednesday: Cold air in the valleys, warmer air up high that is expected to get close to 0C above 2200m. Some valley cloud is possible, clear at upper elevations. Light variable winds.Thursday: Clear in the morning, cloud developing through the day. Inversion conditions expected to persist. Moderate southwesterly winds.Friday: Cloudy with some flurries. Freezing level creeping up to around 1000 m. Some warm air remaining at higher elevations. Moderate southwesterly winds

Avalanche Summary

On Sunday, a size 1.5 avalanche involving two people near Invermere was reported. It was suspected to have run on the mid-December weak layer. On Saturday a skier triggered size 2 persistent slab avalanche running on a layer of facetted snow from mid-December was reported. This happened in the north of the region's Dogtooth Range on a west aspect at 2400m. Expect the potential to trigger persistent slabs to increase as last week's storm snow continues to settle into a cohesive slab.

Snowpack Summary

20-40 cm low density new snow has accumulated and buried a recently formed layer of weak feathery surface hoar and/or sugary facets. Another layer buried mid-December that consists of surface hoar, sun crust and/or sugary facets is down approximately 40-70cm and has been reported at elevations up to 2400 m. The likelihood of triggering avalanches on either of these layers is related to how dense the upper snowpack is. In areas where the upper snowpack has settled into a firmer slab, the weak layers below are more likely to be triggered. A rain crust that formed in late November is now buried 70-110cm deep. Recent reports show this layer to be unreactive at this time.

Problems

Persistent Slabs

An icon showing Persistent Slabs
A weak layer of surface hoar buried 30-50 cm deep is expected to become more reactive as warmer temperatures help settle recent new snow into a cohesive slab.
Approach steep open or sparsely treed slopes cautiously.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

Wind Slabs

An icon showing Wind Slabs
Wind slabs have been reported and are likely to continue to develop in exposed terrain. Warmer temperatures at higher elevations may also make the upper snowpack denser.
If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind loaded snow.

Aspects: North, North East, East, South East, South, South West.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Jan 3rd, 2018 2:00PM

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