Avalanche Forecast

Issued: Dec 18th, 2014 8:25AM

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

jfloyer, Avalanche Canada

South Rockies.

Mainly sluffing and thin wind slabs in the alpine until a storm on Sunday brings a bit more snow with warming temperatures.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

Flurries for Friday then moderate snowfall on Sunday. Friday: 2-3 cm new snow expected with moderate to strong southwesterly ridgetop winds. Freezing level around 1200 m. Saturday, no snow until the evening; during the day there should be some sunshine, especially in the morning. Freezing level around 1400 m. Sunday: 5-10 cm new snow expected with freezing levels going to around 2000 m. Ridgetop winds gusting to 80 km/h from the southwest.

Avalanche Summary

No new reports of avalanches from the region on Tuesday or Wednesday morning.

Snowpack Summary

Surface hoar has grown on top of 10-20 cm loose dry snow that has been sluffing readily on a thick hard supportive rain crust that extends into alpine elevations. In the alpine, winds have been conducive to blowing this low density snow into thin wind slabs in exposed lee areas. At treeline and below, the near surface crust is effectively bridging triggers from penetrating to deeper persistent weaknesses that formed earlier in the season. However, on alpine slopes above the recent rain line poorly bonded crusts, facets, and/or buried surface hoar may be susceptible to triggers. Professionals are still concerned with a buried crust from November, down 50-70 cm, that could be triggered by large loads.

Problems

Loose Dry

Dry surface snow is poorly bonded to the underlying hard crust and sluffing off in steep terrain.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>On steep slopes, pull over periodically or cut into a new line to manage sluffing.>Be very cautious with gully features.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Wind Slabs

Winds are expected to be at the ideal strength to transport the low density snow that lies on the surface and set up thin but touchy wind slabs.

Avoid slopes with variable snowpack depths. Avalanches may be triggered from thin spots around boulders or small trees.>Avoid large alpine slopes that have a deeply buried crust with facets. >

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

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Dec 19th, 2014 2:00PM