Avalanche Forecast
Issued: Mar 1st, 2020 5:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
astclair,
Avalanche Canada
Strong winds and incremental snowfall are expected to continue to build wind slabs at upper elevations. In the northern part of the region, buried weak layers require careful evaluation and terrain selection.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations. Uncertainty is due to extremely variable snowpack conditions reported through the region.
Weather Forecast
Sunday: Cloudy, up to 5 cm of snow, strong southwest winds, freezing level 500 m.Â
Monday: Mostly cloudy, up to 5 cm of snow, strong southwest winds, freezing level 1300 m.
Tuesday: Mix of sun and cloud, scattered flurries with up to 5 cm of accumulation, strong southwest winds, freezing level rising to 1500 m.
Wednesday: Decreasing cloud, 5-10 cm of snow overnight, strong southwest wind decreasing to light, freezing level 1000 m.Â
Avalanche Summary
Over the weekend, recent small (size 0.5-1.5) wind slab avalanches were reported breaking 20-30 cm deep on lee features near and above treeline. Periods of strong solar radiation on Saturday initiated pinwheels, rollerballs, and small wet loose avalanches on steep, sunny slopes.
Snowpack Summary
Incremental snowfall and strong winds from the southwest are expected to continue to build reactive wind slabs at upper elevations. 20-30 cm of snow has accumulated since Friday, with 30+cm in the south of the region (i.e. Coquihalla). Strong southwest winds have been redistributing the storm snow into wind slabs on lee features at upper elevations and rapidly loading cornices.Â
In the northern part of the region (i.e. Duffey/Hurley/Goldbridge), a weak layer of sugary faceted snow and feathery surface hoar from February 22 may be buried 40-70 cm deep and warrants careful evaluation. There is high uncertainty regarding the distribution of this weak layer in the region. However, where it does exist, conditions may be prime for human-triggering. Check out the latest forecaster blog that offers a deeper dive into these conditions.
Also in the northern part of the region (i.e. Duffey/Hurley/Goldbridge), a deep instability exists at the base of the snowpack. It has not produced recent avalanche activity since February 17th. Rapid warming or heavy loading by new snow/wind/rain events have the potential to re-awaken this layer.
Terrain and Travel
- Pay attention to the wind, once it starts to blow fresh sensitive wind slabs are likely to form.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
Problems
Wind Slabs
Incremental snowfall and strong southwest winds are expected to continue to build reactive wind slabs on lee features at upper elevations. These areas of concern overlap with where cornices may also be reaching their breaking point.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
In the north of the region (e.g. Duffey, Hurley, Goldbridge) on sheltered slopes near and above treeline, a layer of surface hoar from February 22 may be buried under 40-70 cm of snow. Recent snow, wind, and solar radiation may have promoted cohesion in the slab above this layer, priming it for human triggering. Travelling near steep, open slopes at upper elevations warrants an investigation of this layer.
Deeper in the snowpack, a weak layer of facets near the ground presents a lingering concern on steep, shallow slopes in the alpine.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 2nd, 2020 4:00PM
