Archived

Avalanche Forecast

Dec 11th, 2015–Dec 12th, 2015

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

1: Low

The avalanche danger rating below treeline will be low

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

1: Low

The avalanche danger rating below treeline will be low

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

1: Low

The avalanche danger rating below treeline will be low

Regions: Northwest Coastal.

Conditions below tree-line vary greatly with elevation. Many areas are still below the threshold for avalanches but buried surface hoar may be present as you approach tree-line.

Confidence

Low - Due to the number of field observations

Weather Forecast

SATURDAY: Flurries with up to 10cm localized to costal regions, light southwest winds, freezing level at 500m SUNDAY: mainly clear, moderate south east winds, freezing level at valley floor 1000m. MONDAY: mainly clear with flurries possible in the afternoon, light northwest winds, freezing level at valley floor.

Avalanche Summary

Widespread avalanche activity was reported through recent storm, with several avalanche releasing on the layer of surface hoar now buried between 70cm and 1m deep. Natural activity on this layer has slowed since the storm ended on Thursday. Explosive avalanche control around Shames produced smaller storm slab avalanches that released on mid-storm instabilities under larger triggers.

Snowpack Summary

Up to a meter of settled snow fell in the last week which may be sitting upon a layer of buried surface hoar. This layer has the potential for remote triggering and wide propagations. It is likely to be lurking on sheltered north facing slopes at or just below tree-line although it has been spotted well into the alpine in Bear Pass. Strong north through easterly winds overnight on Thursday have reverse loaded lee features. Low, below tree-line elevations may still be bellow threshold for avalanches in many places.

Avalanche Problems

Persistent Slabs

Human triggered avalanches are still possible, especially on North facing terrain at, and just below tree-line due to a layer of buried surface hoar.

Avoid open slopes and convex rolls at and below treeline where buried surface hoar may be preserved.>Carefully evaluate terrain features by digging and testing on adjacent, safe slopes.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 2 - 5

Wind Slabs

Moderate to strong north through east winds have created soft slabs in lee features both at ridge-top and on cross loaded slopes.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3