Avalanche Forecast

Issued: Dec 16th, 2014 7:31AM

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

Avalanche Canada rbuhler, Avalanche Canada

A deeply buried weak layer remains a concern, especially on steep north facing slopes in the alpine. Remote triggering of this layer may still be possible.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

The high pressure will continue to dominate for Wednesday and Thursday. On Wednesday, expect a mix of sun and cloud and treeline temperatures around -8C. Thursday will be mostly cloudy with light scattered flurries possible (0-2cm). Treeline temperatures should be around -6C. On Friday, the high pressure begins to break down as a weak system pushes into the interior from the coast. Precipitation amounts are forecast to be 2-4mm with treeline temperatures around -5C. Alpine winds are expected to remain light from the SW-W for the forecast period.

Avalanche Summary

No new avalanches were reported by publish time on Tuesday. On Monday, explosive control produced a size 3 deep slab avalanche and a snowmobile triggered a size 1.5 wind slab. On Sunday, a report of a skier remotely triggering a size 2.5 avalanche from 5 meters away in the Dogtooth range alpine. This occurred at around 2300m in the alpine. Also reported was an explosive triggered size 2 persistent slab releasing around 60cm deep.

Snowpack Summary

A surface crust exists up to around 2200 m. Above this elevation is dry storm snow which is settling out and faceting. A new layer of surface hoar is currently forming on the snow surface. In exposed alpine terrain, strong southerly winds last week may have resulted in variable distribution of the surface snow and the formation of wind slabs. The early November crust/facet layer is down around 1 m. Tests are suggesting that this layer is getting difficult to trigger but still has the potential to produce large avalanches. We received reports that this deep weak layer has resulted in remotely triggered avalanches over the weekend.

Problems

Deep Persistent Slabs

An icon showing Deep Persistent Slabs
The likelihood of triggering a deep persistent slab has decreased but the consequences remain very high. Be wary of any slopes that did not release during the storms. Heavy triggers such cornice falls may be able to trigger a deep weak layer.
Avoid common trigger zones including thin snowpack areas, near rocky outcrops, and steep alpine slopes.>Remote triggering is a concern, watch out for adjacent slopes.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Dec 17th, 2014 2:00PM