Archived

Avalanche Forecast

Dec 18th, 2013–Dec 19th, 2013

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

3: Considerable

The avalanche danger rating below treeline will be considerable

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

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.

The storm continued overnight, depositing more snow with strong winds. Good group management, minimizing exposure to overhead hazard, and conservative terrain selection are highly recommended.

Weather Forecast

As the storm exits the region we should get lingering flurries this morning, with moderate winds shifting to the NW as an arctic ridge of high pressure moves in. We may see some sunny breaks this afternoon, and Thursday looks sunny and cold with temps dropping to -20 overnight. Friday will be cloudy and snowing with strong SW winds at ridgetop.

Snowpack Summary

80cm of storm snow sits over a variety of surfaces from December 8th like surface hoar lower down, facets and variable wind slabs at higher elevations. Strong winds have formed windslabs and wind loaded pockets above treeline. Below this are 2 persistant weak layers and the snowpack is facetted. As the load increases these layers may wake up.

Avalanche Summary

A widespread natural avalanche cycle continues. Most were initiated in the alpine and at treeline, running well into runouts, but several triggered slabs below treeline. Along the highway, 1 size 3.5, 4 size 3 and 20 size 2 avalanches were observed yesterday. On Monday skiers reported large natural avalanches occurring up the Connaught drainage.

Confidence

Intensity of incoming weather systems is uncertain

Avalanche Problems

Storm Slabs

This weeks storm deposited 80cm of snow under ideal slab forming conditions. This slab sits on a weaker surface that may be reactive to skiers and riders, and the slab is deep enough to produce large avalanches.

Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.Choose conservative lines and watch for clues of instability.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 2 - 4

Wind Slabs

Strong winds throughout the storm, with lots of snow available for transport, have loaded lee slopes and formed windslabs at treeline and above.

Avoid freshly wind loaded features.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 2 - 3

Persistent Slabs

Buried surface hoar down between 80 to 110cm with a recent significant snow load should remain a concern for rider triggering. These layers may also be triggered by other avalanches, producing very large avalanches.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 3 - 4