Avalanche Forecast

Issued: Nov 30th, 2017 3:54PM

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 stormy weather has dumped as much as 110 cm of new snow on last week's crust. This has created reactive storm slabs and there have been reports of large avalanches. Use a conservative approach and terrain selection.

Summary

Confidence

Low - Due to the number and quality of field observations

Weather Forecast

Friday: Snow amounts 5-15 cm with moderate South West wind. Alpine temperature -5. Freezing level 500 m and dropping.Saturday: Snow amounts 5-10 cm with light to moderate South West wind. Alpine temperature -7. Freezing level valley bottom.Sunday: Mix of sun and cloud. Light to moderate North West wind. Alpine temperature -7. Freezing level valley bottom. Visit the Mountain Weather Forecast for more details.

Avalanche Summary

No recent natural avalanche activity has been reported. On Wednesday, an explosive triggered slab avalanche was reported up to size 2.5 in the alpine. The aspect is unknown. Earlier in the week, observations from the Shames area reported audible avalanches from across the valley and shooting cracks within the recent storm snow. The recent storm snow will likely take time to settle and bond. Travel in avalanche terrain will require conservative route selection and terrain choices. Please send your recent observations to the Mountain Information Network. Give info get info.

Snowpack Summary

Snow accumulations of 80-100 cm of storm snow in the southern part of the region now lies on the supportive 5-10 cm thick, November 23 rain crust from last week. Winds associated with the new snow has formed reactive wind slabs on leeward slopes. Below this crust is a weak layer that formed in late October and is now buried 120-160 cm within the snowpack. Beneath this October crust is a 20-30 cm thick layer consisting of several thin crusts and facets (sugary snow). Recent snowpack tests and observations indicate that that the new snow is likely reactive to rider triggers.Reports further north near Ningunsaw, describe a much shallower facetted snowpack 60-120 cm.

Problems

Storm Slabs

Building storm slabs will be most prominent and reactive to rider triggers above treeline especially where the storm snow has been affected by the wind.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.The new snow will require several days to settle and stabilize.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 3

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.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 4

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