Avalanche Forecast

Issued: Dec 16th, 2018 4:27PM

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

Avalanche Canada mbender, Avalanche Canada

Forecast precipitation amounts have been reduced over the coming days. However there is a buried weak layer that is within the range of human triggering. A conservative approach to choosing terrain is recommended in the coming days.

Summary

Confidence

Low - Forecast snowfall amounts are uncertain

Weather Forecast

SUNDAY Night: Rain 5-10mm, snow above 1300m, accumulation 5-10 cm. Alpine temperature -4. Moderate south wind.  Freezing level 1300 mMONDAY: Rain showers or flurries, accumulation 5-10 cm. Alpine temperature -2. Light to moderate southwest wind. Freezing level 1400 mTUESDAY: Snow, accumulation 10-20 cm. Alpine temperature -1. Moderate to strong southwest wind. Freezing level 1500 m.WEDNESDAY: Flurries, accumulation 5cm. Alpine temperature -3. Light south wind. Freezing level 1200 m

Avalanche Summary

Explosive control work along the Duffey Lake road on Friday produced avalanches up to size 2.5 running on the weak layer of facets buried 60 to 80 cm below the surface. A remotely triggered size 1.5 avalanche in the Coquihalla Summit backcountry suggests this same layer is a concern there.

Snowpack Summary

Up to 1 m of new snow fell since the storm pattern started last Sunday. Strong southerly winds distributed new snow into variable wind slabs in exposed locations. A crust at or near the surface likely exists up to approximately 1700 m.Below the recent storm snow lies a weak layer, comprising 20-30 cm of low density faceted snow. Initially, the snow did not bond well to this layer. While it's likely gaining strength, field observations show that slab avalanches remain possible on this layer.Near the base of the snowpack, a crust exists that previously had sugary facets. This could potentially still be of concern in high north facing areas in drier parts of the region. Elsewhere, this layer is no longer a concern.

Problems

Wind Slabs

An icon showing Wind Slabs
Some new snow combined with wind has developed fresh wind slabs in the lee of terrain features.
Be cautious as you transition into wind affected terrain.Use ridges or ribs to avoid pockets of wind loaded snow.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
A weak layer buried approximately 70 cm below the surface has the potential to produce large avalanches.
Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Dec 17th, 2018 2:00PM