Avalanche Forecast

Issued: Nov 27th, 2018 3:24PM

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

Avalanche Canada jfloyer, Avalanche Canada

Recent new snow has improved riding quality. But avalanche hazard will linger after the storm.

Summary

Confidence

Low - Due to the number of field observations

Weather Forecast

TUESDAY NIGHT: Flurries with moderate southwesterly winds.WEDNESDAY: Occasional flurries with some clear spells. Moderate southwesterly winds. Freezing level around 1400 m.THURSDAY: Dry with a mix of sun and cloud. Light southwesterly winds. Freezing level around 1200 m.FRIDAY:    Dry with a mix of sun and cloud. Calm winds. Freezing level around 600 m.

Avalanche Summary

It's unlikely there was quite enough snow for much natural avalanche activity to have occurred during the storm on Monday or Tuesday. However, human-triggered avalanches will remain a concern on steep, smooth slopes for a few days after the storm ends. On Saturday, a large human triggered avalanche was reported in the South Columbia forecast region. The size 3 avalanche occurred on a steep, north aspect in the alpine and failed to ground, likely on the October crust. This avalanche is notable for the Purcells where we have a similar, but shallower snowpack than in the South Columbia, resulting in a higher possibility of impacting a weak layer near the ground. Find the MIN report here.

Snowpack Summary

Approximately 20 cm new snow fell in this area during the most recent storm, which will have been blown into wind slabs on exposed northerly and northeasterly slopes. In most places, there are two layers of feathery surface hoar being reported, one around 20cm below the surface and one around 35cm. One or both of these may be associated with a crust on south aspects. The most likely places to trigger one of these layers is in deeper snow areas in shady spots on smooth slopes. A final, prominent feature of the snowpack is a combination of a crust and underlying sugary, faceted snow found near the base of the snowpack. It may still be possible to release an avalanche on smooth slopes in the alpine.

Problems

Storm Slabs

An icon showing Storm Slabs
Recent new snow and wind will have set up storm and wind slab problems that are most likely to give problems on steep, smooth, north to east facing slopes.
Caution in lee and cross-loaded terrain near ridge crests.Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Persistent Slabs

An icon showing Persistent Slabs
A nasty combination of crust and sugary, faceted snow exists at the base of the snowpack in the alpine. This layer could produce avalanches on steep, smooth slopes in the alpine.
If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Nov 28th, 2018 2:00PM

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