Avalanche Forecast

Issued: Dec 4th, 2018 4:16PM

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

Avalanche Canada ghelgeson, Avalanche Canada

Fresh and potentially human triggerable wind slabs may form in the alpine Tuesday night. While unlikely, it may be possible to trigger a large avalanche in steep, smooth, alpine bowls where a dense slab rests on a weak base.

Summary

Confidence

Low - Due to the number of field observations

Weather Forecast

The high amplitude ridge sitting off the BC Coast is expected to deflect any potential storm systems away from the province this week. The forecast period is marked by cooler temps, clear skies and no significant precipitation with no change expected for the foreseeable future.TUESDAY NIGHT: Freezing level at valley bottom, light southerly wind at most elevations, strong to extreme northwest wind at ridgetop, no significant precipitation expected. WEDNESDAY: Scattered cloud cover, freezing level at valley bottom, light variable wind, no significant precipitation expected. THURSDAY: Clear sky, freezing level at valley bottom, light variable wind, no significant precipitation expected.FRIDAY: Clear sky, freezing level at valley bottom, light southwest wind at low elevations, moderate northwest wind at ridgetop, no significant precipitation expected.

Avalanche Summary

No new avalanches have been reported in the region. If you have been out, please submit any observations to the Mountain Information Network MIN.

Snowpack Summary

The region received up to 20 cm of snow over the past seven days. Isolated pockets of stiff wind slab may exist on leeward slopes. Below the surface exists a series of crusts and a feathery surface hoar layer. We have a lot of uncertainty around the weak surface hoar layer and its distribution, but it's most likely present on sheltered slopes in the alpine and at treeline. A mixed layer of melt-freeze crusts and sugary facets buried late October can be found at the base of the snowpack at treeline and in the alpine. This layer has not been active, but there is potential for slab avalanches on this layer given the current snowpack structure. Terrain features like smooth alpine bowls with variable snowpack depths would be most suspect.Average snowpack depths at treeline are near 50 cm and taper quickly as elevation decreases. Snow depths below treeline are generally below the threshold depth required to produce avalanches.

Problems

Wind Slabs

An icon showing Wind Slabs
There is not a lot of fresh snow to form into new slabs, but strong to extreme northwest wind Tuesday night may create fresh wind slabs which are likely to be most sensitive to human triggering immediately lee of ridgecrest and in extreme terrain.
Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Increase your caution as you transition into wind affected terrain.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 1.5

Valid until: Dec 5th, 2018 2:00PM

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