Avalanche Forecast
Issued: Apr 28th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs, Loose Wet and Cornices.
mconlan,
Avalanche Canada
A high freezing level will destabilize the snowpack, potentially triggering numerous different avalanche problems. Check out the latest Forecasters' Blog for more information.
Summary
Confidence
Moderate
Avalanche Summary
We haven't received any recent avalanche observations.
We expect a strong uptick of avalanches on Saturday as the freezing level is above mountain tops. Expect to see loose wet or slab avalanches, cornice falls, lingering wind or storm slabs, and potentially large avalanches releasing on buried weak layers.
Snowpack Summary
Warm air to the mountain tops will moisten the snow surface. Wind slabs may be found in steep, lee terrain features from recent snow and strong southerly wind. Storm slabs could prevail in wind-sheltered terrain. These slabs may sit on a hard melt-freeze crust found up to 1400 m and to mountain tops on sun-exposed slopes. They could release as wet slab avalanches as the upper snowpack moistens.
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
Saturday will see a freezing level to 2300 m with periods of rain. Light rain or snow is expected for Sunday and Monday with a freezing level around 1500 m and 1200 m, respectively. The wind is expected to remain moderate to strong from the south to southwest.
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
Loose Wet
Wet loose avalanche activity is expected 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 the recent storm overlies a hard melt-freeze crust.
Aspects: All aspects.
Elevations: Alpine, Treeline.
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: Apr 29th, 2023 4:00PM
