Avalanche Forecast
Issued: Mar 2nd, 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 continue to build wind slabs at upper elevations. Deeper instabilities cannot yet be discounted.
Summary
Confidence
Moderate - Uncertainties in both the snowpack structure and the weather forecast limit our confidence. Uncertainty is due to the limited number of field observations.
Weather Forecast
Monday night: Mostly cloudy, 3-8 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 1400 m.
Wednesday: Mix of sun and cloud, 5-10 cm of snow overnight, moderate southwest wind decreasing to light, freezing level 1000 m.
Thursday: Mostly cloudy, up to 5 cm of snow, 10-15 cm possible near the Coquihalla, strong southwest wind, freezing level rising to 1500 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.Â
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 (30+cm near the Coquihalla), with winds redistributing the storm snow into slabs on lee features and rapidly loading cornices.Â
A weak layer of sugary faceted snow (and possibly feathery surface hoar in isolated areas) from February 22 may be found 40-70 cm deep. Although there has been little avalanche activity on this layer, recent snowpack test results suggest that a propensity for human triggering may still linger. See this MIN for a helpful illustration.
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
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
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
A layer of weak facets (and possibly surface hoar in isolated areas) from February 22 may be buried 40-70 cm deep. Although there has been little reported avalanche activity on this interface, snowpack test results suggest that a propensity for human triggering may still linger.
In the north of the region (e.g. Duffey, Hurley, Goldbridge), a deeper 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 3rd, 2020 3:00PM
