Sea to Sky Avalanche Forecast

Issued: Apr 10th, 2021 4:00PM

Sun Apr 11th Current Conditions
Alpine Moderate Treeline Moderate Below Treeline Low
Mon Apr 12th 2 Day Outlook
Alpine Moderate Treeline Moderate Below Treeline Low
Tue Apr 13th 3 Day Outlook
Alpine Moderate Treeline Low Below Treeline Low

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs, Loose Wet and Cornices.

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

High -

Weather Forecast

Saturday night: Clearing. Moderate northwest winds easing to light by morning.

Sunday: Mainly sunny. Light north winds. Alpine high temperatures around -6 with freezing levels to 1400 metres.

Monday: Sunny. Light northeast winds. Alpine high temperatures around -3 with freezing levels to 1700 metres.

Tuesday: Sunny. Light northeast winds. Alpine high temperatures around 0 with freezing levels to 2100 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 a slippery crust lower down, and natural loose wet activity on steep slopes where sun exposure destabilized the surface. This mix of hazards was almost certainly more pronounced in the south of the region, which saw up to triple 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 10-30 cm of new snow, with a strong southern focus, accumulated through Friday night with strong to extreme south and east winds. Whistler Peak saw gusts of up to 140 km/h. The new snow brings storm totals from this week to about 25-50 cm. Collectively, this recent snow sits on a crust on sun-exposed aspects, and on all aspects below about 1600 m. It likely sits on soft snow or on older wind slabs on north aspects. 

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

An icon showing Wind Slabs

Likelihood

Possible

Expected Size

1 - 2

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.

Loose Wet

An icon showing Loose Wet

Likelihood

Likely

Expected Size

1 - 1.5

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.

Cornices

An icon showing Cornices

Likelihood

Possible

Expected Size

2 - 3

Cornices are large and looming along many ridgelines, and have likely grown with recent fresh snow and wind.

Aspects:

North, North East, East, West, North West.

Elevations:

Alpine.

Valid until: Apr 11th, 2021 4:00PM

Forecast Trend

The latest forecast danger ratings, broken down to elevation. See how an elevation is trending.