Change is in the air, but even short periods of sunshine combined with high freezing levels can pack a punch to an already weak snowpack. Loose wet avalanches and wet slab avalanches remain possible on Friday.
Steer clear of cornices from above and below.
Summary
Confidence
Moderate - Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.
Weather Forecast
Overnight Thursday: Clear with some cloud cover and a light wind. Alpine temperatures near +3 and freezing levels 1600 m.Â
Friday: Mostly cloudy with some sunny periods. Ridgetop wind light to moderate from the South. Alpine temperatures near +3 and freezing levels 1600 m.
Saturday: Precipitation 10-20 mm falling as snow in the high alpine and rain below. Ridgetop wind moderate from the South. Alpine temperatures near 0 and freezing levels 1400 m.
Sunday: Precipitation 5-10 mm. Ridgetop wind light from the South. Alpine temperatures near -2 and freezing levels 1300 m.Â
Avalanche Summary
No recent avalanche observations have been submitted from this region.
In the neighboring Sea to Sky region and the South Coast Inland, multiple wet slab avalanches and wet loose avalanche activity have been active throughout the week as large as size 4 but primarily in the size 2-3 range. Many of these involved the full depth of the snowpack, running to the valley bottom. We suspect similar activity to have occurred in the South Coast region as well.
Cornices remain weak and fragile. They require a large berth from above and below as they are very unpredictable.Â
Snowpack Summary
High overnight freezing levels continue, the snowpack is reportedly isothermal on southerly aspects to the mountain top and all aspects to treeline elevations. A cooling trend will slowly begin tonight forming a surface crust at upper elevations. In places where the surface forms a crust overnight, it should quickly soften during the day with sunshine and warm temperatures. The highest elevation north aspects (above 2200 m) may still hold some dry snow.
Cornices are large and looming along ridgelines. They are weak and very unpredictable.
Terrain and Travel
- 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
Loose Wet
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
Wet Slabs
The likelihood of wet slab avalanches increases during prolonged periods of warm temperatures, as the heat penetrates deeper into the snowpack. In the neighboring Sea to Sky Region and South Coast Inland several very large wet slab avalanches have been observed in the last couple of days. These avalanches are dense, destructive, and can run far, reaching otherwise snow-free valley bottoms.
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 23rd, 2021 4:00PM
