Issued: May 3rd, 2023 4:00PM
The alpine rating is Storm Slabs, Deep Persistent Slabs and Cornices., the treeline rating is , and the below treeline rating is Known problems include
Newly formed slabs could be touchy and wet avalanches are possible during the heat of the day. Be aware of the variety of avalanche problems that you could come across during spring weather.
Riders could trigger newly formed storm or wind slab avalanches within the snow that accumulated on Tuesday with strong southerly wind.
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.
New storm and wind slabs likely accumulated at alpine elevations on Tuesday, with the most snow near White Pass and Haines Pass and less as you move east. The snow accumulated on a hard melt-freeze crust. The snow surface may moisten during daytime warming, particularly on sun-exposed slopes.
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.
Spring-like weather prevails for the coming days, with overnight cooling and daytime freezing levels rising to around 1300 m on Thursday, 2000 m on Friday, and 1400 m on Saturday. A mix of sun and cloud is expected,
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Carefully evaluate steep lines for wind slabs.
- 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.
Recent snow and strong southerly wind likely formed new storm slabs and wind slabs. Assess for slabs in high consequence or steep terrain before committing yourself.
Wet avalanches are possible at lower elevations on on sun-exposed slopes during the heat of the day.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Deep Persistent Slabs
Weak layers may be found in the middle and near the base of the snowpack, which may 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.
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.
Valid until: May 4th, 2023 4:00PM