Avalanche Forecast

Issued: Dec 13th, 2015 8:48AM

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

jlammers, Avalanche Canada

Sea To Sky.

Patience, Grasshopper. The snowpack needs time to adjust to the load of the new snow. I'd give it a few days before pushing into steep alpine terrain.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

A mix of sun and cloud is expected for the forecast period, although light flurries are possible on Tuesday. Ridge top winds should remain generally light and northwesterly with freezing levels hovering between 500m and 800m. For a more detailed weather overview, check-out the Mountain Weather Forecast at: avalanche.ca/weather

Avalanche Summary

At the time of publishing, there was little information available regarding avalanche activity in the region. However, there were some reports of explosive controlled storm slabs to size 2.5 in lee alpine features. In at least one case, the avalanche failed on a rain crust approximately 100cm below the surface.

Snowpack Summary

Up to 45cm of new snow has be shifted by strong southerly winds into much deeper and potentially reactive storm slabs in lee terrain. Below 1800m, reports suggest there is much less wind effect and therefore less cohesion in the newly formed slab.Below 2200m, a hard rain crust can be found approximately 120cm below the surface. Recent tests suggest an improving bond at this interface. That said, in some areas the crust may remain reactive for some time after weaknesses within the storm snow have strengthened. I'd dig and test this layer before committing to any steeper exposed lines.

Problems

Storm Slabs

Natural activity has tapered-off, but human-triggered storm slab avalanches remain a concern, especially in high elevation lee terrain. I'd give the snowpack a few days to adjust to the load of the new snow before pushing into any steep alpine lines.

The new snow may require several days to settle and stabilize.>Be cautious as you transition into wind affected terrain.>Be alert to conditions that change with elevation.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Cornices

Recent wind and snow have formed new and potentially unstable cornices. Use extra caution when approaching ridge crests.

Stay well back from cornices.>Extra caution needed around cornices with current conditions.>

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Dec 14th, 2015 2:00PM