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Archived

Avalanche Forecast

Dec 8th, 2020–Dec 9th, 2020
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
3: Considerable
The avalanche danger rating below treeline will be considerable
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Little Yoho.

Lots of new snow in Little Yoho - 20 cm in Field and at least 30 cm at Emerald Lake settled into a warm, wet slab over surface hoar and crust. Below treeline is tricky now for the first time this winter. Keep it mellow and easy for a few days.

Weather Forecast

A strong SW flow over continues over the area, although the bulk of the moisture has passed. Expect another 5-10 cm by mid day Wednesday, then a clearing trend and wind following the storm. Temperatures will fall and perhaps even reach -20 by Thursday.

Snowpack Summary

20-30 cm of wet snow has been deposited on top of the Dec 8 layer of surface hoar, sun crust and facets and produces easy test results at the storm snow interface. This indicates a poor bond with the new snow. Over the next 24-hours this snow will settle into a more cohesive slab and the bond will not improve due to the weak layer.

Avalanche Summary

No observations above treeline today, but below treeline in Little Yoho was active with many sluffs and small slabs observed in the Mt Dennis ice climbs, approximately 15-20 cm deep by 2-3 m wide. Watch out on gully walls ice climbers.

Confidence

Avalanche Problems

Storm Slabs

There is a lot going on with this new snow, so be conservative and observe how it effects the snowpack. We have wind slab up high, storm slabs at and below treeline and lots of loose snow avalanches in cliffs and steep chutes. All on a PWL.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 2.5

Deep Persistent Slabs

The Nov 5 crust has facets above and below it, and exists up to 2500m on shady aspects and higher on solar aspects. No new observations since the storm, but we expect it may become more reactive with the additional load.

  • Be aware of thin areas that may propogate to deeper instabilites.
  • Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 2.5