Avalanche Forecast
Issued: Mar 9th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
kdevine,
Avalanche Canada
Recent storm snow has been redistributed into pockets of wind slab at tree line and in the alpine and may continue to be reactive. Watch for denser, deeper drifts near ridge-crests and rollovers.
Summary
Confidence
Weather Forecast
TUESDAY NIGHT - Mainly cloudy with clear periods / light to moderate southwest wind / alpine low temperature near -7
WEDNESDAY - Mainly cloudy with sunny breaks and isolated flurries / light to moderate southwest wind / alpine high temperature near -6 / freezing level
1500 m
THURSDAY - Mainly sunny / light northwest wind / alpine high temperature near -6 / freezing level 1600 m
FRIDAY - Mainy sunny / light to moderate west wind / alpine high temperature near -3 / freezing level 1800 m
Avalanche Summary
On Monday, there were reports of small wet loose avalanches on solar aspects and a few small dry loose avalanches.
On Saturday, operators reported ski cutting small (size 1) pockets in the recent storm snow. Observers also reported loose dry sluffs in the new snow in steep terrain. See this MIN report for an example.
During last week's warm weather, a large (size 2) slab avalanche released naturally on a weak layer of facets near the ground in a shallow snowpack area east of the region near Apex.
The most recent avalanche observed on the late January persistent weak layer was reported February 28th, when large explosives produced very large (size 2-3) results at Kootenay Pass.
Snowpack Summary
Up to 20 cm of snow accumulated over the weekend in a few areas (Big White and Kootenay Pass). Periods of moderate winds from the southwest have likely formed shallow wind slabs in lee features at upper elevations. The new snow fell on a variety of old snow surfaces including hard wind-pressed snow, a melt-freeze crust, or settled powder in sheltered, shaded areas. Additionally, a thin layer of surface hoar may also exist at this interface that could increase the likelihood of triggering wind slabs.
Deeper in the snowpack, a persistent weak layer from late January is buried 80-150 cm deep and is composed of a combination of surface hoar, crusts, and facets. There is some lingering uncertainty about whether this problem remains reactive on isolated upper elevation slopes on solar aspects, in thin snowpack areas.
As described in this MIN report, shallow snowpack areas in the east of the region may harbor a faceted basal snowpack. This structure can typically be managed by avoiding shallow rocky areas where the snowpack transitions from thick to thin.
Terrain and Travel
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Wind Slabs
Incremental snowfall and moderate winds from the southwest have formed shallow wind slabs in lee features at upper elevations that may be possible to trigger.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 10th, 2021 4:00PM
