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 - Uncertainty is due to how the snowpack will react to the forecast weather. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
 Monday night: Cloudy, 5-10 cm of snow, strong west winds, freezing level 1300 m.
Tuesday: Cloudy, up to 5 cm of snow, moderate southwest winds, gusting strong at ridge-top, freezing level 1100 m.Â
Wednesday: Partly cloudy, 5-15 cm of snow overnight, moderate west winds decreasing to light, freezing level 900 m.
Thursday: Cloudy, 20-30 cm of snow, strong southwest winds, freezing level 1000 m.Â
Avalanche Summary
On Sunday and Monday, there were reports of small, human-triggered wind slabs on lee features at upper elevations. Check out this MIN for a helpful example.Â
During the weekend storm, observers reported a natural avalanche cycle of small to large (size 1-2.5) slab avalanches releasing in the recent snow 20-40 cm deep. Recent explosive mitigation has also triggered several large cornices. Periods of strong solar radiation Saturday afternoon initiated pinwheels, rollerballs, and small wet loose avalanches on steep, sunny slopes.
On Wednesday, a large (size 2) human-triggered avalanche releasing on the February 22 surface hoar was reported. Â
Snowpack Summary
20-30 cm of snow has accumulated since Friday. Strong winds redistributed the storm snow into reactive wind slabs on lee features at upper elevations and rapidly loaded cornices.Â
Buried 40-70 cm deep, a weak layer of sugary faceted snow and feathery surface hoar from February 22 may persist and warrants careful evaluation. Operators observed recent reactivity in snowpack tests and reported whumpfing in terrain near Tricouni. Check out the latest forecaster blog that offers a deeper dive into these conditions.
Faceted snow and crusts exist near the base of the snowpack in much of the region. This layer is has been dormant recently.
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.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
Problems
Wind Slabs
Incremental snowfall and strong west 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, South, 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, observers have reported whumphing and snowpack test results that suggest a propensity for human triggering may still linger.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 3rd, 2020 3:00PM
