Avalanche Forecast
Issued: Dec 6th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Loose Wet and Deep Persistent Slabs.
dsaly,
Avalanche Canada
With new flurries and wind, keep a look out for wind slabs building through the day.
Summary
Confidence
Weather Forecast
SUNDAY NIGHT: Cloudy and flurries, up to 5 cm / Moderate to strong, southwest ridgetop wind / alpine low temperature -4 / Freezing level 1200 m
MONDAY: Flurries and wet snow, 5-15 cm / Strong, southwest ridgetop wind / alpine high temperature +1 / Freezing level rising to 2000 m
TUESDAY: Flurries, 5-15 cm / Moderate, gusty southwest ridgetop wind / alpine high temperature +1 / Freezing level dropping to 1500 m
WEDNESDAY: Isolated flurries / Light southwest ridgetop wind / alpine high temperature -3 / Freezing level 1000 m
Avalanche Summary
On Saturday, a few wet loose avalanches to size 2 were observed from steep rocky features in the sun. Outside of a few other small wet loose avalanches from steep terrain, there have been no avalanche observations since last Wednesday (Nov 2) when a widespread wet loose avalanche cycle up to size 2 was triggered by warming.
Of note to consider in the Duffy area: A notable avalanche occurred last Tuesday (Nov 1) when a large size 3 natural avalanche was observed on a NE aspect at 2400 m. It was reported as a cornice failure triggering the slope below and appeared to have slid on the early November crust near the base of the snowpack.
Have you been out and about in the mountains? If so please submit to the Mountain Information Network (MIN). It doesn't have to be technical it can be as simple as a photo. Photos are especially helpful! Sending out a big thank you to the already submitted MIN's this season. Thanks everyone!
Snowpack Summary
A melt-freeze crust covers most slopes resulting from recent sun and warm temperatures. Where cold, dry snow prevailed (upper elevations on more shaded and polar slopes), winds continue to press slabs into lee features. Large surface hoar growth has been observed in treeline areas sheltered from the warm temperatures, sunshine and wind.
The lower snowpack is characterized by a few crusts that formed during warm periods in November.
- In the north, treeline snowpack depth sits around 80 to 150 cm. The crust of note here is sitting near the base of the snowpack, likely surrounded by a weak layer of sugary facets. Snowpack tests and recent avalanche activity suggest that this layer could be triggered by humans and produce large avalanches.
- In the south of the region, treeline snowpack depth sits around 120-190 cm. Melt-freeze snow surfaces exist after the recent warming. The deeper crusts in this area are generally down around 60-80 cm in the alpine and well bonded to surrounding snow.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be alert to conditions that change with elevation and wind exposure.
- Back off slopes as the surface becomes moist or wet with rising temperatures.
- When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
Problems
Wind Slabs
Expect increasing slab development as wind redistributes flurries accumulating throughout the region. The most reactive slabs will be in wind-loaded areas or around ridges and convex rolls.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
As freezing levels spike late Monday (and areas that get rain instead of snow), a wet loose hazard will persist anywhere the snowpack is moist or wet.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
In the north of the region (e.g., Duffey Lake), a weak layer of sugary faceted grains around a hard melt-freeze crust sits near the base of the snowpack. Be wary of overhead hazards, a large impact (like a cornice failure - see avalanche summary) could trigger the slope below. There is a lot of uncertainty on the reactivity of this layer - we're keeping it on our radar because we don't have enough information. And if this layer is triggered, it will likely produce large avalanches. This problem does not exist in the south of the region.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 7th, 2020 4:00PM
