Avalanche Forecast
Issued: Mar 16th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Storm Slabs.
zryan,
Avalanche Canada
Practice good travel habits and choose conservative, low consequence lines. A buried weak layer has been reactive in recent days, creating large and surprising avalanches.
Make sure to read the Avalanche Problems section.
Summary
Confidence
Weather Forecast
A series of frontal systems coming in off the coast will bring light precipitation throughout the week.
Wednesday Overnight: Mainly cloudy, light snowfall, up to 5 cm of accumulation. Freezing level dropping to 900 m. Moderate to strong southwest winds.
Thursday: Cloudy with snowfall, 5-15 cm of accumulation. Freezing level rising to 1500 m. Moderate to strong southwesterly winds.
Friday: Partially cloudy, light flurries. Freezing level rising to 1500 m in the afternoon. Light to moderate southwesterly winds.
Saturday: Mainly cloudy, light flurries. Freezing level around 1000 m. Light to moderate southwesterly winds.
Avalanche Summary
Riders may get surprised by widely propagating persistent slabs that are sitting on a weak layer of surface hoar. Remote-triggering is a concern. Be aware of above and adjacent slopes.
Tuesday was an active day for avalanche activity. Throughout the region, operators reported numerous natural and human-triggered storm slabs. These slabs mainly occurred on north-facing (shaded) aspects in the alpine and treeline and failed on a buried weak layer of surface hoar. The most reactivity has been noted near Blue River, Valemont, and south of McBride.
Snowpack Summary
Continued light precipitation will add to 30-60 cm of recent settling storm snow at treeline and above. Storm snow tapers rapidly below treeline, where moist snow or a melt-freeze crust can be expected from rain and warm temperatures.
This new snow is sitting on various surfaces, including hard wind-affected snow, sun crusts on southerly slopes, facetted snow, and isolated pockets of surface hoar. The new snow is bonding poorly to this old surface, especially where a facet/crust layer or surface hoar is present below.
The lower snowpack is generally well-settled and strong in most areas, with prominent crust layers 50 to 100 cm deep. No recent persistent slab avalanches have been reported on these layers.
Terrain and Travel
- Conservative terrain selection is critical, choose only well supported, low consequence lines.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Surface hoar distribution is highly variable. Avoid generalizing your observations.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
Problems
Persistent Slabs
Over the past week, 40-80 cm of new snow buried a weak layer of surface hoar and facet/crust. This layer has been most reactive on shaded aspects at treeline, but caution should be taken on all aspects as this problem unfolds. Terrain features to be particularly cautious of include the lee side of ridges, openings in trees, cut blocks, and burns. Remote-triggering is a concern. Be aware of above and adjacent slopes.
The most reactivity on this layer has been seen in the McBride, Valemount, and Blue River corridors.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Storm Slabs
30-80 cm of recent snow, warm temperatures, and moderate southwest winds have formed storm slabs that have been most reactive in wind-affected terrain. Continued snowfall and wind throughout the day will build fresh and reactive slabs.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Mar 17th, 2022 4:00PM
