Avalanche Forecast
Issued: Apr 10th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Loose Wet and Cornices.
cgarritty,
Avalanche Canada
Stay tuned in to hazards lingering from the storm. Wind slabs perched in steep leeward pockets, looming cornices, and fresh snow seeing its first sun exposure will all need to be managed on Sunday. Greater new snow accumulations mean greater hazard in the south of the region.
Summary
Confidence
Weather Forecast
Saturday night: Clearing. Light northwest winds.
Sunday: Mainly sunny. Light north winds. Alpine high temperatures around -6 with freezing levels to 1400 metres.
Monday: Mainly sunny. Light northeast winds. Aline high temperatures around -3 with freezing levels to 1700 metres.
Tuesday: Sunny. Light to moderate northeast winds. Alpine high temperatures around 0 with freezing levels to 2000 metres.
Avalanche Summary
We don't yet have reports showing the results of Friday's storm, but it's likely that surface instabilities were quite active on Saturday, with a mix of wind slab hazards in higher elevation, wind exposed terrain, potentially storm slabs over slippery crust lower down, and natural loose wet activity where sun poked out to destabilize surface snow. This mix of hazards was almost certainly more pronounced in the south of the region, which saw 2-3 times the accumulations of the north.
Looking forward, the new snow is likely to form a reasonable bond with the old surface by Sunday, however recently wind loaded areas and slopes that see solar warming should remain suspect over the near term.
Snowpack Summary
About 10 cm of new snow fell in the north of the region through Friday night, closer to 20-30 cm near the Coquihalla, with amounts tapering off with elevation. Moderate to strong southwest winds accompanied this snowfall, moving snow into thicker, more reactive slabs in leeward terrain features. The new snow adds to 10-20 cm that fell last weekend.
Collectively, this new and recent snow sits on a crust in most areas, except on north aspects above about 1500 m where it sits on older wind slabs or soft snow, depending on wind exposure.
Cornices are large and looming along ridgelines and they formed fragile new growth during the storm. Their release is unpredictable, requiring a large berth if you're travelling above or below them.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Loose avalanches may start small but they can grow and push you into dangerous terrain.
- Pay attention to cornices and give them a wide berth when traveling on or below ridges.
Problems
Wind Slabs
Slab problems are likely to be restricted to wind loaded features by Sunday, but pinning down slab distribution may be tricky with winds that shifted north after the storm. Analyze slopes for wind loading patterns and test small, low-consequence features before stepping out. This problem will be most pronounced in the south of the region.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Wet
Surface snow will lose cohesion and become unstable with solar warming during the day. Avoid exposing yourself to terrain where a small wet loose release could have big consequences.
Aspects: South East, South, South West, West.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Cornices are large and looming along many ridgelines, and have likely formed fragile new growth with recent snow and wind.
Aspects: North, North East, East, West, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Apr 11th, 2021 4:00PM
