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Avalanche Forecast

Dec 15th, 2018–Dec 16th, 2018
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable

Regions: South Coast Inland.

Incoming storms will drive the avalanche hazard for the next few days. The days for playing it safe and conservative continue!

Confidence

Moderate - Intensity of incoming weather systems is uncertain

Weather Forecast

SATURDAY NIGHT: 20 to 30 cm new snow in places like the Coquihalla, I expect a little less further north (e.g. Duffy Lake). Freezing level around 800 m. Moderate southerly winds.SUNDAY: Another 20 to 30 cm new snow. Freezing level around 1700 m. Moderate to strong southerly winds.MONDAY: Continued snow with an additional 15 to 25 cm of snow. Freezing level around 1500 m. Moderate southwesterly winds.TUESDAY: Storm continues with more snow, possible as much as 25 cm. Freezing level steady around 1500 m. Moderate to strong southwest winds.

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.

Avalanche Problems

Storm Slabs

Forecast new snow amounts of up to 50 cm by Sunday evening will rapidly increase avalanche hazard.
The new snow will require several days to settle and stabilize.Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Very Likely

Expected Size: 1 - 2.5

Persistent Slabs

A weak layer buried approximately 70 cm below the surface has the potential to produce large avalanches. And, it's only going to get deeper with even bigger avalanches possible ...
Use conservative route selection, choose moderate angled and supported terrain with low consequence.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1.5 - 3