Avalanche Forecast

Issued: Nov 30th, 2017 4:16PM

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

Avalanche Canada jlammers, Avalanche Canada

This forecast is based on very few field observations and a high level of uncertainty exists. A conservative approach to terrain selection is critical until more snowpack data becomes available.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Friday: 4-8cm of new snow / Moderate to strong southwest winds / Freezing level at 900mSaturday: Light flurries / Light and variable winds / Freezing level at 400mSunday: Mix of sun and cloud / Light and variable winds / Freezing level at valley bottom with alpine temperatures dropping to about -1

Avalanche Summary

On Tuesday and Wednesday explosives control in the north of the region triggered a few storm slabs in the size 2-2.5 range in north-facing alpine terrain. On Tuesday in the Dogtooth range a skier was accidentally caught in a size 2 storm slab on a northwest facing slope at 2350m. The skier was uninjured in the avalanche which was about 40cm deep and 180m long..We currently have very limited observations in this region. Please submit your observations to the Mountain Information Network (MIN).

Snowpack Summary

Last week, the November 23rd crust formed as temperatures cooled and the rain-soaked snow surface froze. Since then, 20-60cm of snow has fallen at treeline and above with moderate to strong southwest winds, creating wind slabs sitting on a crust. Two other layers have been reported in the snowpack: 1) The Halloween crust (down 100cm at treeline elevations) and 2) The November 10th surface hoar / facets (down 80cm at treeline elevations). We have very little information on how reactive these layers are. In fact, we currently have very limited snowpack observations within this entire region and it is critical to supplement this information with your own observations.The depth of the snowpack varies greatly with elevation. Recent reports suggest the average depth is 150+cm in the alpine, 100-150cm at treeline, and decreasing rapidly below treeline where the primary hazards are rocks, stumps, and open creeks.

Problems

Storm Slabs

An icon showing Storm Slabs
Recent wind and snowfall has likely formed reactive new storm slabs. Storm slabs may be more reactive in heavily wind-exposed terrain, or in areas where the new snow has a weak bond with underlying crusts.
Be cautious as you transition into wind affected terrain.Watch for signs of instability such as whumpfing, cracking or recent natural avalanches.The new snow may require several days to settle and stabilize.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 1st, 2017 2:00PM

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