Avalanche Forecast

Issued: Dec 17th, 2012 9:18AM

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

pgoddard, Avalanche Canada

Sea To Sky.

Summary

Confidence

Fair - Intensity of incoming weather is uncertain on Wednesday

Weather Forecast

Tuesday: Light SW winds. Alpine temp -12. A few cm snow.Wednesday: Strong S winds. Alpine temp -8. Heavy snow (~40 cm).Thursday: Light to moderate S winds. Alpine temp -9. Moderate to heavy snow (~30 cm).

Avalanche Summary

Recent activity has been limited to a few small (size 1-1.5) soft slab avalanches in immediate lee features and small loose snow avalanches in steep terrain.

Snowpack Summary

New snow depths are highly variable and decrease as you go inland. 40-80 cm of recent storm snow overlies a thin layer of surface hoar in some areas. Wind slabs are buried on many exposed slopes in the alpine and near treeline from previous winds. New wind slabs are likely to form as low density snow will be easily shifted by forecast strong southerly winds. The mid-pack is well settled and strong.A layer of surface hoar that formed during late November has been found intact or decomposing in some locations down a metre or more. The early November crust/facet combination near the base of the snowpack seems to be dormant. Triggering one of these persistent weak layers from a shallow snowpack area remains possible.

Problems

Wind Slabs

New and buried wind slabs exist on many slopes due to changing winds. Be alert for these below ridge crests, behind terrain features, and in cross-loaded gullies.

Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Use ridges or ribs to avoid pockets of wind loaded snow.>

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

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

2 - 5

Loose Dry

In areas protected from the wind, fast-moving sluff could knock you off your feet or carry you into a terrain trap.

On steep slopes, pull over periodically or cut into a new line to manage sluffing.>Be aware of party members below you that may be exposed to your sluffs.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 4

Valid until: Dec 18th, 2012 2:00PM