Avalanche Forecast

Issued: Jan 19th, 2021 4:00PM

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

Avalanche Canada ahanna, Avalanche Canada

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A windy night has likely resulted in fresh wind slabs reverse loaded into atypical alpine features. Watch for these pockets especially at ridge crests and on steep roll-overs.

Summary

Confidence

High -

Weather Forecast

TUESDAY night: Flurries, trace, strong to extreme ridgetop wind easing to light northwest, freezing level 500 m.

WEDNESDAY: Mix of sun and cloud, light ridgetop wind, alpine high -4, freezing level 800 m.

THURSDAY: Mix of sun and cloud, light wind, alpine high -7, freezing level 700 m.

FRIDAY: Sunny, light wind, alpine high -7, freezing level 500 m.

Avalanche Summary

A few small wind slab and wet loose avalanches were reported on Sunday and Monday. Explosive control targeting cornices on Friday and Saturday produced size 2 results, some triggering deep slabs on the rocky slopes below. 

There has been significant deep persistent slab activity this month. During a widespread avalanche cycle last week, several storm slabs stepped down to deeper weak layers resulting in very large (size 3-4) deep persistent slab avalanches (see these photos from Panorama Ridge). On Jan 9, a large (size 3) avalanche was remotely triggered by skiers on Cowboy Ridge near Whistler. The avalanche occurred on a north to northwest aspect at around 1900 m. The crown was up to 200 cm deep and was approximately 200 m wide. See this MIN for photos and more information. A similar avalanche was remotely triggered by skiers on a nearby westerly slope a few days before (see this MIN).

Snowpack Summary

Ski quality in the extensively wind affected alpine has been widely referred to as chalky. Soft snow may be found in sheltered areas around treeline. A widespread surface crust exists below 1900 m and on south-facing slopes.

Remnants of a melt-freeze crust from early December may be found around 200 cm deep in the snowpack. Several large natural and human triggered avalanches failed on this layer earlier this month. Recent reports and snow profiles suggest that it is decomposing and/or bonding to surrounding snow and trending dormant... for now at least.

Terrain and Travel

  • Be carefull around freshly wind loaded features.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.

Problems

Wind Slabs

An icon showing Wind Slabs

Strong overnight wind from the northwest has likely blown any available loose snow into small but reactive fresh wind slabs in leeward terrain features at upper elevations.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 1.5

Cornices

An icon showing Cornices

Cornices have grown large, saggy and fragile. A few recent cornice falls have triggered avalanches on the slopes below.

Aspects: North, North East, East, North West.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1.5 - 2.5

Valid until: Jan 20th, 2021 4:00PM

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