Large and destructive wet slab avalanches have recently been active. Start and finish your day early to avoid exposure to sun-exposed avalanche terrain.
Steer clear of cornices overhead and plan your egress route carefully.
Summary
Confidence
Moderate - Confidence is due to a stable weather pattern with little change expected. Uncertainty is due to the limited number of field observations.
Weather Forecast
Tuesday: Sunny with light wind. Alpine high temperature near +6 and freezing level 2400 m.
Wednesday: A mix of sun and cloud with light wind. Alpine high temperature near +7 and freezing level 2600 m.
Thursday: A mix of sun and cloud and li9ght wind. Alpine tempertures near +6 and freezing levels 2400 m.Â
Avalanche Summary
Over the weekend, multiple large to very large wet slab avalanches were observed near Whistler, size 2-4. Many of these involved the full depth of the snowpack, running to valley bottom.
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Solar triggered wet loose avalanches have been reported each day over the past week up to size 2.5. There have also been a number of cornice failures reported over the past week.
Snowpack Summary
A slight dip in overnight freezing levels combined with radiant cooling has formed a melt-freeze crust from 1700-2200 m. Reports indicate that this crust is approximately 15 cm thick but will likely break down quickly with solar radiation and freezing levels through the roof. At lower elevations the snowpack is isothermal. Steep north aspects above 2200 m and higher may still hold dry wintery snow.
Cornices are large and looming along ridgelines. Sun and warm temperatures will increase the chances of cornice failures, especially when temperatures remain above zero overnight.
Terrain and Travel
- Avalanche hazard is expected to to increase througout the day, think carefully about your egress.
- Avoid slopes when the solar radiation is strong, especially if they have large cornices overhead.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
- Keep in mind that wet avalanches can be destructive due to their high density.
- Avoid lingering or regrouping in runout zones.
Problems
Wet Slabs
The likelihood of wet slab avalanches increases during prolonged periods of warm temperatures, as the heat penetrates deeper into the snowpack. Multiple very large wet slab avalanches have been observed in the last couple days. These avalanches are dense, destructive and can run far, reaching otherwise snow-free valley bottoms.
Wet loose avalanche activity can also be expected on sun exposed slopes and below treeline. These avalanches are generally smaller than wet slabs but they can gather mass as they travel and reach low elevations.
Aspects: East, South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Cornices are at their largest at this time of year, and become weaker with warm temperatures and solar radiation.
Aspects: North, North East, East, West, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 20th, 2021 4:00PM
