Archived

Avalanche Forecast

Dec 28th, 2016–Dec 29th, 2016

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

4: High

The avalanche danger rating in the alpine will be high

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

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Glacier.

Lots of light snow, combined with lots of wind, will cause new slabs to develop. Combine those hazards with the Christmas ski crowd and managing risk and exposure can be challenging. Remember that people might be above, or below you!

Weather Forecast

Today should be mostly cloudy with flurries bringing up to another 5-10cm. This will add to the ~30cm available for moderate to strong SW winds to transport and load lees. On Thursday, the next storm arrives dumping another ~20cm with gusty SW winds. By Friday the storm will start to taper off, with more flurries and gusty winds.

Snowpack Summary

Another 30cm of snow overnight, combined with strong SW winds, is building a new storm slab. It overlies surface hoar that was observed well into the alpine. Last weeks storm snow is settling into a stiffer slab, and the facetted Dec.18 layer is now down ~1m. Natural and skier triggered slabs on this layer have been observed recently.

Avalanche Summary

Yesterday skiers reported triggerable windslabs on a SW aspect at 2100m on McGill, and there were several size 2 and a size 3 natural avalanche from steep paths east of Rogers Pass. On Monday, a size 2 skier-triggered avalanche from steep, shallow, unsupported terrain carried a person over a large cliff and resulted in a rescue.

Confidence

Intensity of incoming weather systems is uncertain

Avalanche Problems

Storm Slabs

Up to 30cm of snow fell in the last 24hrs at treeline. Combined with SW winds, expect deep loaded pockets to exist on lee slopes. This new slab has buried a surface hoar layer that was spotty in its distribution and may catch people by surprise.

Ski short pitches and regroup in safe spots.Carefully evaluate terrain features by digging and testing on adjacent, safe slopes.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3

Persistent Slabs

The weak, facetted snow from the cold snap in early December is now buried ~70-100cm. The slab over this layer is developing, and as the load on this layer grows it may become increasingly reactive.

Avoid unsupported slopes.Minimize overhead exposure during periods of heavy loading from new snow, wind.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 3

Loose Dry

In areas sheltered from the wind there is a lot of amazing, low density powder. Expect sluffing when skiing steeper pitches. With all the loose, light snow a small avalanche may pick up mass especially in more confined gully type terrain features.

Use caution above cliffs where small avalanches may have severe consequences.Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible - Likely

Expected Size: 1 - 2