Avalanche Forecast

Issued: Dec 2nd, 2018 3:49PM

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

Avalanche Canada cgarritty, Avalanche Canada

We're on a positive track with last week's avalanche problems mostly stabilized, but you can likely still find trouble spots of wind slab and cornice in the alpine.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Sunday night: Cloudy with clear periods. Light northwest winds.Monday: Mainly sunny. Light northeast winds. Alpine high temperatures around -7.Tuesday: Mainly sunny with some valley cloud. Light northwest winds. Alpine high temperatures around -1 under a mild temperature inversion.Wednesday: Sunny. Light northeast winds. Alpine high temperatures around -1 under a mild temperature inversion.

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.Skies cleared on Tuesday, allowing some observation of avalanches that likely released at the height of the storm. A large (size 2.5) avalanche was reported on a northeast facing glacial feature between 2100 and 2200 m. The avalanche failed naturally with a crown up to 1 meter in depth. Another large natural avalanche (size 2) was reported from a north facing feature near 2000 m. Please submit any observations you have to the Mountain Information Network here,

Snowpack Summary

The storm from early last week brought intense precipitation that rain-soaked the snowpack up to about 1800 m and left 20 to 30 cm of wet snow in place up to 2000 m. Above 2000 m the storm produced around 60 cm of new snow. The upper 20 to 30 cm of this snow is reportedly dry in the alpine. Strong to extreme south winds during the storm left behind thick wind slabs and fragile new cornice growth in high elevation alpine terrain. Above 2000 m, 50 to 200 cm of snow now sits on the early November melt-freeze crust. This crust may be associated with weak faceted crystals in some 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

Wind Slabs

An icon showing Wind Slabs
Steady cool temperatures continue to reduce the sensitivity to human triggering of lingering wind slabs, however slabs in extreme terrain and immediately lee of ridgecrest will take the longest to stabilize.
Be cautious around the lee side of ridges and ribs where slabs may be deeper and more sensitive.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 1.5

Cornices

An icon showing Cornices
Cornices formed along many alpine ridgelines during last week's storm and many failed naturally or with explosives in the days after the storm. 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 3rd, 2018 2:00PM