Avalanche Forecast
Issued: May 1st, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Deep Persistent Slabs and Cornices.
mconlan,
Avalanche Canada
New slabs may form on Tuesday. Be aware of the variety of avalanche problems that you could come across during spring weather.
Summary
Confidence
Avalanche Summary
A rider triggered a storm slab on a steep northeast aspect at 1900 m on Friday. Tuesday may see similar avalanches during stormy conditions.
We could see a variety of avalanche problems resurface during spring weather. Milder weather and periods of sun or rain promote wet loose or slab avalanches. Snow near the mountain tops could form storm slabs or wind slabs in lee terrain features. Cornices are large and looming and are more prone to fail which each day of relatively mild weather. The likelihood of triggering buried weak layers also increases in the spring, as the snowpack progressively warms up.
Snowpack Summary
Snow will accumulate above a hard melt-freeze crust and moist snow. Storm and wind slabs are likely to form with the snow and strong southwest wind, and they may not bond well to the snowpack.
A weak layer of facets and potentially a melt-freeze crust from early January is between 100 and 200 cm deep in most areas.
Weak faceted grains may exist near the base of the snowpack, particularly in shallower snowpack areas.
Cornices are very large and looming along alpine ridges.
Weather Summary
Tuesday may see 10 to 20 cm of snow above around 1000 m with local enhancements possible and strong southwest wind. Wednesday and Thursday see a mix of sun and cloud with isolated flurries and daytime freezing levels around 1000 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for fresh storm slabs building throughout the day.
- Wind slabs are most reactive during their formation.
- Avoid avalanche terrain during periods of heavy rain.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Minimize exposure to overhead avalanche terrain, large avalanches may reach the end of runout zones.
Problems
Storm Slabs
Snow and strong wind will form new storm slabs and wind slabs. Assess for slabs in high consequence or steep terrain before committing yourself.
Wet loose avalanche activity may spike if it is raining hard at lower elevations.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Weak layers may be found in the middle and near the base of the snowpack, which are likely to reawaken with the variety of weather we receive during the spring. Small avalanches and cornice falls have the potential to trigger these deeper layers. Human triggered avalanches are most likely in steep, shallow, and rocky terrain where the snowpack is relatively thin.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Cornices
Cornices are large at this time of year and will become more prone to fail as they warm up with spring weather. Stay well back from them when on ridgelines and limit your exposure when travelling on slopes below them, as their release is unpredictable. Cornice falls could trigger very large slab avalanches on slopes below.
Aspects: North, North East, East, West, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: May 2nd, 2023 4:00PM
