Avalanche Forecast

Issued: Nov 27th, 2012 9:21AM

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

Avalanche Canada jlammers, Avalanche Canada

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain

Weather Forecast

Wednesday will see mostly cloudy skies with snowfall developing late in the day. Moderate snowfall will continue throughout Thursday and Friday. Winds will be moderate to strong from the west on Wednesday switching to strong and southwesterly for Thursday and Friday. Freezing levels should remain at about 1200m for the forecast period.

Avalanche Summary

A size 2 sled-triggered slab avalanche occurred on Sunday in the Yanks Peak area. It was on a northwest aspect at 1900m. For more details, check-out our Incident Data Base.

Snowpack Summary

Healthy amounts of snow fell throughout last week. Although alpine wind data has been sparse, velocities in neighboring regions were in the upper end of moderate during the storms. That said, I'd be highly curious about the possibility of windslabs in exposed areas. Although storm slab reactivity is still possible, a break in the snowfall over the last few days has most likely given the upper snowpack a chance to settle and gain some strength. There may be a thin buried surface hoar layer down about 85 cm in the alpine. As well, the November rain crust now exists over 100cm down in some locations and may exist in combination with facets. This layer has shown sudden planar test results.A you're traveling through the mountains, be on the look-out for current surface hoar development and think about how it will affect the snowpack as new snow arrives over the next few days.

Problems

Storm Slabs

An icon showing Storm Slabs
Storm/wind slabs formed last week have gained significant strength, although triggering may still occur on steep, unsupported terrain. Forecast winds may also form new windslabs.
If you are increasing your exposure to avalanche terrain, do it gradually as you gather information.>Be cautious around freshly wind loaded features.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Persistent Slabs

An icon showing Persistent Slabs
There is a variable crust that exists in the lower snowpack. Watch for triggering on unsupported terrain at higher elevations or within start zones with smooth ground cover.
Conditions are greatly improved, but be mindful that deep instabilities are still present.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Nov 28th, 2012 2:00PM