Avalanche Forecast
Issued: Feb 10th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Storm Slabs.
cgarritty,
Avalanche Canada
Keep your head on a swivel as you approach wind exposed-terrain. A range of older, stubborn and newer, more reactive wind slabs can be found across a wide range of aspects. Large hard wind slabs on alpine features should be especially concerning.
Summary
Confidence
Weather Forecast
Wednesday night: Clear. Light northeast winds.
Thursday: Sunny. Light northeast winds, increasing in the afternoon. Alpine high temperatures around -22.
Friday: A mix of sun and cloud. Light east or southeast winds. Alpine high temperatures around -19.
Saturday: Cloudy with light flurries continuing from the overnight period bringing about 5 total cm of new snow, easing overnight. Light southeast winds. Alpine high temperatures around -12.
Avalanche Summary
Snowfall focused in the Coquihalla zone resulted in heightened storm slab activity over the weekend. Several natural and skier triggered avalanches averaging size 1-2 were reported. These occurred mostly on south aspects where a reactive storm slab layer formed over a slippery crust.
In the north of the region, recent avalanche activity has mainly been limited to skier triggered wind slabs size 1-1.5, however a very notable size 3 (very large) persistent slab was remotely triggered (from a distance) by a group of skiers in the McGillivray Pass area on Monday. This occurred on a southwest aspect at 2400 metres. It was described as a hard wind slab formed over our facet layer from late January.
Snowpack Summary
A stormy period from 4 to 8 February dropped approximately 60 cm of new snow in the Coquihalla, 40 cm near Allison Pass and 20 cm in the north of the region. This snow likely sits on a slippery crust on solar aspects, and possibly surface hoar elsewhere. A number of avalanches were triggered on this layer in the Coquihalla on Sunday. Snowpack tests on Wednesday revealed reactivity at this interface has since become more resistant.
An earlier persistent weak layer that was buried around January 24 sits some way below the recent storm snow. This consists of facets at upper elevations, surface hoar in sheltered areas and a crust on south-facing slopes. An isolated very large avalanche on this layer in the north of the region is discussed in our avalanche summary. It averaged about 100 cm deep in that location. Whumpfs were also recently reported on this layer in the south of the region, indicating this layer might remain a concern there as well.
In the north, a melt-freeze crust from early December may be found 100 to 200 cm deep. Recent reports suggest that this layer is gaining strength and it has been unreactive in recent weeks.
Terrain and Travel
- Carefully evaluate steep lines for wind slabs.
- Watch for areas of hard wind slab on alpine features.
- Be aware of highly variable recent wind loading patterns.
Problems
Wind Slabs
Wind slabs may be reactive to human triggers, especially more recent formations and where slabs have formed over a crust (think solar aspects). Increase your caution even more around large, hard wind slabs in alpine areas. these may overlie weak, sugary faceted snow.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Storm Slabs
Specific to the south of the region, a preserved layer of low density snow (over a crust) about 50 cm deep may still have some potential to be human-triggered on steep, primarily south-facing slopes in more sheltered areas.
Aspects: South East, South, South West.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Feb 11th, 2021 4:00PM
