Avalanche Forecast

Issued: Dec 29th, 2014 7:33AM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs.

Avalanche Canada ghelgeson, Avalanche Canada

Shifting winds are likely forming wind slabs in unusual locations.

Summary

Confidence

Poor - Due to the number of field observations

Weather Forecast

Synopsis: Arctic air to dominate for a few days, then warming from the north. Outflow winds should reach their peak Monday night. By Tuesday afternoon warmer Pacific air associated with the offshore upper ridge should move inland opening the door to a potential inversion or an above freezing layer between 1500 & 2500m.Tuesday: Freezing Level: Valley Bottom; Precipitation: Nil; Wind: Treeline: Light, NE | Ridgetop: Strong, NE.Wednesday: Freezing Level: Valley Bottom, potential AFL 1500 2500m; Precipitation: Nil; Wind: Treeline: Light, Variable | Ridgetop: Strong, N.Thursday: Freezing Level: Valley Bottom, potential AFL 1500 1500m; Precipitation: nil; Wind: Treeline: Light, Variable | Ridgetop: Moderate, NW

Avalanche Summary

A naturally-triggered size 2 slab was observed on Saturday on an alpine NE aspect in steep, windloaded terrain. A naturally-triggered size 1.5 wind slab was also observed at treeline on a north aspect in the Hankin area, which probably failed on Wednesday or Thursday. On Tuesday we received a report of a size 1.5 skier remotely triggered avalanche in the far north of the region. It released on a steep, wind loaded feature and was triggered from 5m away. The 25-45 cm thick slab occurred around 1600 m elevation.

Snowpack Summary

10-20 cm of new snow from Friday night is likely being formed into fresh wind slabs on lee slopes as winds shift into an outflow pattern. Older wind slabs from previous westerly winds are buried underneath. A layer of buried surface hoar down about 30-50 cm appears to be spotty in distribution, but may still be a concern in some areas. Near the base of the snowpack, the mid-November crust-facet layer has become less likely to trigger, but is still in the back of our minds.

Problems

Wind Slabs

An icon showing Wind Slabs
Reverse wind loading driven by strong outflow winds is likely forming fresh sensitive wind slabs on lee features. Be alert for breakable, drummy or punchy snow conditions which may indicate wind slabs.
Travel on ridgetops to avoid wind slabs on slopes below.>Avoid freshly wind loaded features.>Be alert to wind slab conditions, which may be found on a variety of slope aspects. Wind slabs may look smooth, bulbous or fat. >

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Dec 30th, 2014 2:00PM

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