Avalanche Forecast

Issued: Dec 1st, 2017 4:30PM

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

swerner, Avalanche Canada

Northwest Coastal.

The recent storm snow will need time to settle and may be reactive to rider triggers. Storm slab avalanches could step down and trigger deeper layers within the snowpack, initiating large avalanches.

Summary

Confidence

Low - Due to the number and quality of field observations

Weather Forecast

Saturday: Mix of sun and cloud with isolated flurries and alpine temperatures near -10. Ridgetop winds light from the North West and freezing levels at valley bottom.Sunday: Mix of sun and cloud. Alpine temperatures near -8 and freezing levels at valley bottom. Ridgetop winds light from the West.Monday: Cloudy with 10-25 mm of precipitation. Ridgetop winds moderate from the South West. Alpine temperatures rising to 0 degrees and freezing levels near 1200 m.

Avalanche Summary

On Thursday, reports indicate natural slab avalanche activity up to size 2 from steep alpine features and numerous loose dry size 1 avalanches from steep terrain at all elevations. Please consider submitting your observations this weekend to the Mountain Information Network.

Snowpack Summary

Recent accumulated storm snow amounts are from 100-130cm and sit on a supportive 5-10 cm thick crust that was buried a week ago. The new snow seems to be settling quickly, however; deeper deposits of wind slab may be found on leeward slopes. Digging deeper in the snowpack exists a crust/facet combo buried at the end of October. This crust may exist anywhere from 90 cm-150 cm down. Recent snowpack test results are showing hard compression tests with sudden collapse results. I would keep this on my radar through the weekend to see how the snowpack adjusts to the new load.

Problems

Storm Slabs

Building storm slabs will likely be reactive to rider triggers, especially at upper elevations where the storm snow has been affected by wind.

Be cautious as you transition into wind affected terrain.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Deep Persistent Slabs

This layer has been inactive. However, with the increasing load of new snow this layer may become reactive. Something to keep on your radar.

If triggered the storm slabs may step down to deeper layers resulting in very large avalanches.If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 4

Valid until: Dec 2nd, 2017 2:00PM