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Avalanche Forecast

Apr 3rd, 2012–Apr 4th, 2012
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
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
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

Regions: South Coast.

Confidence

Good

Weather Forecast

Unsettled conditions in the wake of Tuesday's storm system are expected to produce cloudy conditions and isolated light flurries with a few centimetres each day for the forecast period. The freezing level is expected to drop to and remain around 800 m, and the winds should remain light and variable.

Avalanche Summary

Reports from Monday are limited to occasional glide avalanche activity to Size 2.5 in the Coquihalla area. Natural avalanches probably occurred on Tuesday in response to heavy loading from snow, wind, and/or rain. Check out the telemarktips.com South Coast conditions forum for a report of a remotely triggered Size 3 slab avalanche on a north facing couloir in the east side of the Duffey Lake area on Sunday. The slab failed on basal facets and propagated 300m out of the couloir and wrapped around to the adjacent northwest.

Snowpack Summary

As of Tuesday morning, 15cm of new snow in the Duffey Lake area adds to the 40-70cm of snow that fell over the past week, while light rain fell in the Coquihalla area. The past week's snowfall overlies a predominately crusty interface, except north facing slopes at treeline and above where small surface hoar (5mm) may be found. Recent reports include hard but sudden compression tests results and a Rutschblock 4 whole block failure on this late-March surface hoar in the Duffey Lake area. In the north of the region, persistent early February layers linger deeper and could fail as large step-down slabs. Cornices are huge and potentially very destructive.

Avalanche Problems

Wind Slabs

Thick fresh wind slabs are highly sensitive to human triggers and cornice falls.Expect to encounter them below ridgecrests, behind terrain features, and in gullies.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 4

Storm Slabs

Storm slabs are sensitive to human triggers and have the potential to step-down to deeper weaknesses resulting in highly destructive avalanches.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 1 - 5

Cornices

Cornices are very large and probably unstable. Not only are they a hazard in themselves, but can also act as a heavy trigger for very large avalanches on the slope below.

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

Elevations: Alpine.

Likelihood: Possible

Expected Size: 1 - 6