Avalanche Forecast
Issued: Feb 1st, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
swerner,
Avalanche Canada
Wind slabs at upper elevations continue to be touchy to skier and rider triggers, especially where they sit above a buried surface hoar/ crust layer.
Summary
Confidence
Weather Forecast
Tuesday: A mix of sun and cloud with isolated flurries. Ridgetop wind light from the northeast. Alpine temperatures near -6 and freezing levels valley bottom.
Wednesday: Snow 5 cm with light ridgetop wind. Alpine temperatures near -6 and freezing levels in the valley bottom.
Thursday: Snow up to 20 cm. Ridgetop wind strong from the southwest and freezing levels rising to 1300 m.
Avalanche Summary
Several small wind slab avalanches were triggered by skiers and riders at treeline and in the alpine on various aspects on Saturday and Sunday (see this MIN report).
As the slab properties start to change, and the recent snow becomes more cohesive (under the influence of wind and settlement) it will likely remain reactive to human triggers, especially where it sits above a surface hoar interface.
Snowpack Summary
15-45 cm of recent snow sits on a crust below 1000 m and surface hoar in sheltered locations at and below treeline. If the recent snow has enough cohesion the slab may be reactive where it sits above these weak layers. This MIN report shows just that.
The layers in the mid and base of the snowpack have gained strength with high snowfall amounts in January. Deeper layers appear to have gone inactive in the southern part of the region. However, in the northern part of the region (e.g. Bear Pass, Ningunsaw) there has still been regular avalanche activity on weak snow at the bottom of the snowpack with large loads such as explosives or cornice collapses.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Watch your sluff: it may run faster and further than you expect.
Problems
Wind Slabs
Moderate southerly wind continues to redistribute the new snow and build fresh wind slabs in lee terrain features in the alpine and exposed treeline. Older wind slabs were formed on westerly aspects and may still be reactive. Wind slabs will be particularly reactive anywhere snow overlies buried surface hoar or crust. The surface hoar layer is likely preserved in sheltered areas at and below treeline. In steep and wind-protected areas loose dry snow avalanches (sluffs) are expected.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 2nd, 2021 4:00PM
