Avalanche Forecast
Issued: Jan 9th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
JSmith,
Avalanche Canada
Extreme southerly winds will form fresh wind slabs on lee features at treeline and above. Avoid freshly wind loaded features, especially near ridge crests, roll-overs, and in steep terrain.
Summary
Confidence
Weather Forecast
SATURDAY NIGHT: Cloudy with isolated flurries; 0-3 cm. / Extreme, south ridgetop wind / alpine low temperature -11 / Freezing level valley bottom.
SUNDAY: Flurries; 3-5 cm. / Extreme, south ridgetop wind / alpine high temperature -6 / Freezing level valley bottom.
MONDAY: Flurries; 3-5 cm. / Strong, southwest ridgetop wind / alpine high temperature -4 / Freezing level 700 m.
TUESDAY: Flurries; 3-5 cm. / Extreme, south ridgetop wind / alpine high temperature -4 / Freezing level 700 m.
Avalanche Summary
Avalanche activity is beginning to slow down. However, previous to Thursday, there had been steady reports of natural wind slab avalanches in alpine terrain (size 1-2), and some smaller human-triggered wind slab avalanches in lee terrain (size 1). There are good photos of these avalanches in recent MIN reports (e.g. here, here, here, and here). While there have been no reports of persistent slab avalanches since Dec 22, there have been recent reports of large whumpfs in the Hudson Bay, Hankin, and Babines area, suggesting that buried weak layers are still possible to human trigger.
Snowpack Summary
Strong wind is moving around 40-60 cm of snow that has fallen since New Year's Day. Reactive wind slabs can be found in exposed open terrain, while lower density snow can be found in sheltered terrain. In some parts of the region this snow could be sitting above a surface hoar layer and forming isolated persistent slabs on steep rolls in sheltered areas below treeline.
The lower snowpack has two crusts with potentially weak snow around them. Reports from the Smithers area suggest the upper crust is 60-90 cm below the surface and has shown signs of being possible to trigger from shallow areas. The other crust is near the bottom of the snowpack, and is most likely to trigger from steep, rocky slopes, with a shallow or thin to thick snowpack.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
- Be especially cautious near rock outcroppings, on steep convexities and anywhere the snowpack feels thinner than average.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
Problems
Wind Slabs
Extreme winds may form fresh wind slabs throughout the day on lee features at treeline and above. Wind slabs in motion may step-down to deeper weak layers resulting in large avalanches.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Triggering large avalanches on weaknesses in the lower snowpack remains a possibility. In some areas the concern is weak snow around crusts 60 to 90 cm deep, while in others it is weak snow near the bottom of the snowpack. Human triggering of these layers are most likely in steep, rocky slopes with a shallow or thin to thick snowpack.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 10th, 2021 4:00PM
