Avalanche Forecast

Issued: Dec 3rd, 2018 4:29PM

The alpine rating is moderate, the treeline rating is low, and the below treeline rating is low. Known problems include Loose Wet and Cornices.

Avalanche Canada cgarritty, Avalanche Canada

Change is in the air with forecast warming and sunshine shifting the focus to surface instabilities on Tuesday.

Summary

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

Monday night: Mainly clear. Light northeast winds. Tuesday: Sunny. Light northwest winds. Alpine high temperatures around -1 with a increasing alpine temperature inversion establishing an above freezing layer at 2000 metres by evening.Wednesday: Sunny. Light northeast winds. Alpine high temperatures around -1 under a continuing alpine temperature inversion with an above freezing layer at 2000 metres.Thursday: Sunny with cloudy periods. Light variable winds. Alpine high temperatures around -1 with a lingering alpine temperature inversion and above freezing layer at 2000 metres.

Avalanche Summary

No new avalanches were reported over the weekend.Explosives control work in the Whistler area on Friday produced several size 1.5 cornice releases and one 20 cm deep size 1.5 storm slab. On Wednesday cornices were touchy; a size 1.5 cornice failure was initiated with a very light load. Control work produced storm slabs that averaged size 1.5 on a variety of aspects in the alpine. The outlier was a size 3 avalanche induced by control work on a north facing alpine feature which stepped down to the early November crust.Please submit any observations you have to the Mountain Information Network here,

Snowpack Summary

Days of cool, clear weather have grown a widespread new layer of feathery surface hoar crystals on the snow surface. Below the surface, the same cold has been transforming the storm snow from last week into a layer of faceted (sugary) snow. This layer of faceting storm snow increases in depth from about 20 cm at 1800-2000 metres, where it sits above a strong rain crust, to upwards of 30-40 cm in the alpine above 2000 metres, where the crust is not present. Here, the storm snow shows good signs of bonding well to the now well-settled mid snowpack.Above 2000 m, about 50-150 cm of snow now sits on the early November melt-freeze crust. This crust may be layered with weak faceted crystals in places where it lies close to the ground. This is most likely to cause problems in glaciated terrain or on smoother, high elevation slopes where the summer snow did not melt out.

Problems

Loose Wet

An icon showing Loose Wet
Rising temperatures and strong sunshine will destabillize surface snow and promote loose wet avalanche activity on sun-exposed slopes on Tuesday. Loose wet slides may occur naturally or with a human trigger.
Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Be aware that low angle December sun tends to target steeper slopes.

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 1.5

Cornices

An icon showing Cornices
Cornices formed along many alpine ridgelines during last week's storm. Cornices weaken with warm temperatures and strong sunshine. Elevate your caution around cornices and avoid travel on or underneath them.
Stay well back from cornices when traveling on or below ridgelines.

Aspects: North, North East, North West.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Dec 4th, 2018 2:00PM