Avalanche Forecast

Issued: Dec 7th, 2019 4:00PM

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

Avalanche Canada MBender, Avalanche Canada

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There is uncertainty with the reactivity of several buried weak layers. Best to adopt a conservative approach while the snowpack adjusts to the increased load from recent snowfalls.

Summary

Confidence

Moderate - Uncertainty is due to field data and reports showing a wide variation in conditions throughout the region.

Weather Forecast

Saturday Night: Flurries, accumulation 1-5 cm, alpine temperature -8, moderate northwest wind.

Sunday: Sunny with cloudy periods, alpine temperature -9, moderate northwest wind.

Monday: Mix of sun and clouds, alpine temperature -7, moderate north wind.

Tuesday: Mix of sun and cloud, alpine temperature -8, light northwest wind. 

Avalanche Summary

Reports from Friday indicate skier triggered and natural storm slab avalanches to size 1-2 within the storm snow. Additionally there were explosives controlled avalanches to size 3 along the Trans Canada highway corridor. On Thursday there were reports of a few explosives triggered size 2.5-3 storm slab avalanches on southeast aspects in the alpine. There were also a few reports of persistent slab avalanches failing on a layer of surface hoar (down 60-80 cm) at treeline elevations. 

Snowpack Summary

20-40 cm of new snow from the past few days has covered a layer of feathery surface hoar that has been found at all elevations in some parts of he region. A thick layer of faceted crystals, previously wind-affected surfaces, and/or surface hoar in sheltered areas (around treeline and below) is now 40-80 cm below the surface.

An additional layer of surface hoar may be found in sheltered areas around treeline down 60-100 cm. In some areas this may sitting on a thin crust.

A variety of crusts from late October are buried deeper in the snowpack. Total snow depths range from 140-200 cm around tree line.

Problems

Storm Slabs

An icon showing Storm Slabs

20-45 cm of new snow accumulating over the past 48 hours has formed a reactive storm slab. In some areas this may be sitting on a layer of weak surface hoar.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs

A surface hoar/crust layer down 60-100 cm has become reactive with the recent storm snow. This layer is most likely found in sheltered openings around treeline and below. 

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1.5 - 3

Valid until: Dec 8th, 2019 5:00PM