Avalanche Forecast

Issued: Jan 1st, 2018 4:56PM

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.

jfloyer, Avalanche Canada

Purcells.

Rapid warming in the alpine and a persistent weak layer 30-50 cm below the surface are both good reasons to be cautious.

Summary

Confidence

High -

Weather Forecast

Tuesday: Cold air in the valleys, warmer air up high. An above freezing layer is expected from approximately 2300-2700 m. Some valley cloud is possible, clear at upper elevations. Light southwesterly winds.Wednesday: basically a repeat of Tuesday, possibly slightly warmer.Thursday: Cloud developing later in the day. Lower elevations getting warmer, although the above freezing layer is expected to remain in place. Light 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.Â 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

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.

Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Approach steep open or sparsely treed slopes cautiously.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 3

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.

Use ridges or ribs to avoid pockets of wind loaded snow.Be cautious as you transition into wind affected terrain.If triggered the storm slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Jan 2nd, 2018 2:00PM