Archived

Avalanche Forecast

Apr 4th, 2012–Apr 5th, 2012

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

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

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

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: Kananaskis.

The current storm could bring another 15 to 20cm of snow by Thursday afternoon. Wind loaded features in the alpine and treeline are the most likely areas for human triggering. large loads, such as cornice failures, could trigger a deeper weak layer.

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain on Thursday

Weather Forecast

Another 15 to 20cm of new snow is possible through the night and into Thursday. Winds will swap from E to N to W and remain light. Temperatures are dropping as are freezing levels. Light flurries are forecast for Friday and Saturday.

Avalanche Summary

Nothing new was observed, but visibility was quite limited.

Snowpack Summary

5cm of new snow has fallen since this morning and it is not yet clear if this is the beginning of the "intense storm" or if the storm has lost some power. Soft slabs continue to form at alpine and treeline elevations and these remain sensitive to triggering in steep, unsupported lee terrain, especially where the slabs sit on buried crusts. The snowpack also continues to settle due to overall warm temperatures. Sun crusts and temperature crusts formed yesterday are now buried under today's snow. Cornices also continue to be a concern as they are large and have become active in recent days.

Avalanche Problems

Storm Slabs

Storm slabs are forming under current weather conditions, adding to the already sensitive wind slabs. These slabs are averaging 40 to 60cm deep and sit on a crust in many locations. Slides may step down as recent avalanche activity has proven.

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

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 2 - 5

Cornices

Cornices are large and have been failing with additional load and/or solar radiation. Cornice chunks themselves are a problem, and several failures have caused large avalanches by triggering the February surface hoar or the basal facets.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 5

Persistent Slabs

The February surface hoar is buried 120-140cm at treeline. This interface is still hard to trigger, but it has come back alive in recent cornice triggered avalanches. The spring transition could see more avalanches stepping down to this layer.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 6