Avalanche Forecast
Issued: Apr 29th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs, Cornices and Loose Wet.
mconlan,
Avalanche Canada
Be aware of the variety of avalanche problems that you could come across during spring weather.
Summary
Confidence
Moderate
Avalanche Summary
A rider triggered a storm slab on steep northeast aspect at 1900 m on Friday. Numerous natural wet loose and storm slabs were also observed in the region.
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 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
Warm air to the mountain tops moistened the snow surface on Saturday, which likely froze into a melt-freeze crust. Rain at lower elevations could re-moisten the snow surface. Lingering wind slabs may be found in steep, lee terrain features from recent snow and strong southerly wind.
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
Sunday to Tuesday sees mostly cloudy skies with some sunny breaks, a freezing level around 1300 m to 1500 m, light rain at lower elevations and snow up high, and moderate to strong south to southwest wind.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- 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.
- Minimize exposure to overhead avalanche terrain, large avalanches may reach the end of runout zones.
- Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.
- Even brief periods of direct sun could produce natural avalanches.
- Carefully evaluate steep lines for wind slabs.
Problems
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
Loose Wet
Wet loose avalanche activity may occur with daytime warming, rain, and any brief sunny period. Limit your exposure to steep terrain when it is raining or if the snow feels sloppy.
Wet slabs are also possible, particularly where recent snow overlies a hard melt-freeze crust.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 30th, 2023 4:00PM
