Avalanche Forecast

Issued: Dec 11th, 2020 4:00PM

The alpine rating is moderate, the treeline rating is low, and the below treeline rating is low. Known problems include Storm Slabs.

Avalanche Canada ahanna, Avalanche Canada

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Watch for reactive pockets of storm slab and solar triggered loose dry avalanches in steep terrain where direct sun grazes dry snow for the first time.

Summary

Confidence

Moderate -

Weather Forecast

Friday night: Clear, light northwest ridgetop wind, freezing level valley bottom.

Saturday: Sunny, light variable ridgetop wind, alpine high -2C, freezing level 700 m.

Sunday: 5-10 cm new snow, light to moderate southwest wind, alpine high -6C, freezing level 700 m.

Monday: 5-10 cm new snow, light southwest wind, alpine high -6C, freezing level 900 m.

Watch David Jones' Whistler Powder Picker weather report from Thursday here.

Avalanche Summary

Since Wednesday, both natural and controlled avalanche activity has been mostly limited to loose dry sluffs of diminishing size. A size 1 skier accidental storm slab was reported on a north aspect at 2000 m, with crown depth 10-30cm.

A widespread natural cycle occurred during the storm Monday night through Tuesday, storm slabs size 2-3 and loose wet size 1-2.

Have you been out and about in the mountains? If so please submit your observations to the Mountain Information Network (MIN). It doesn't have to be technical - photos are especially helpful! Thank you so much for all the great MINs submitted so far! 

Snowpack Summary

5-10 cm of dry snow sits over a crust that formed at all elevations during the warm, wet storm earlier this week. 

At treeline and below, the crust continues to harden with cool temperatures but may still be somewhat punchy, with a moist snowpack below.

In the alpine, the crust is supportive. Sugary facets sit sandwiched between this surface crust ontop, and an ice lens up to 50 cm below the surface. The ice lens formed from the freezing rain that fell on the old snow surface at the beginning of the previous storm. Above 2100 m, it has been a failure plane for avalanches since the storm.

Snowpack depths change rapidly with elevation, from 50-100 cm around treeline to over 150 cm in the alpine.

Terrain and Travel

  • Minimize exposure to steep, sun exposed slopes, especially when the solar radiation is strong.
  • Small avalanches can have serious consequences in extreme terrain. Carefully evaluate your line for wind slab hazard before you commit to it.

Problems

Storm Slabs

An icon showing Storm Slabs

Loose dry avalanches are likely where the sun touches dry snow for the first time. You may also find small pockets of triggerable storm slab near in wind loaded leeward features.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible - Likely

Expected Size

1 - 1.5

Valid until: Dec 12th, 2020 4:00PM