Avalanche Forecast

Issued: Nov 22nd, 2013 8:18AM

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

Avalanche Canada swerner, Avalanche Canada

Forecasts are based on limited observations. You need to be the detective. Dig down, test weak layers and keep an eye on rising temperatures throughout the weekend.

Summary

Confidence

Fair - Due to the number of field observations

Weather Forecast

High pressure will dominate though the forecast period. This will bring warming temperatures, rising freezing levels and temperature inversions. Some forecasts suggest alpine temperatures could rise as high as 5 degrees celsius by Monday. Ridgetop winds will be light from the West and no precipitation is expected.

Avalanche Summary

During the storm earlier this week a widespread natural avalanche cycle in the alpine occurred. Size 2-3 slab avalanches were reported throughout the region. Recently, only smaller size 1-2 avalanches have been reported. However, isolated very large slab avalanches may occur naturally and could be rider triggered, especially in areas that didn't previously avalanche.

Snowpack Summary

Recent storm snow seems to be settling, but wind slab problems do exist. A surface hoar layer exists  60-120 cm down but seems to be spotty, and drainage specific. A bigger concern is a melt-freeze / rain crust that formed early October. This is generally found from 80-180 cm down, and was reactive earlier this week. Sugary facetted crystals have a poor bond above and below the crust. The crust seems to be widespread through the region. Northerly aspects may have a more predominant crust that that might allow for wider propagations and bigger avalanches, especially places that have smooth ground cover (glacier ice, grassy slopes, rock slabs etc.).

Problems

Persistent Slabs

An icon showing Persistent Slabs
Recently, large avalanches have failed on a buried crust that sits near the base of the snowpack. Rider triggers are possible, especially in alpine terrain and areas that did not previously avalanche.
Be aware of the potential for large, deep avalanches due to the presence of a buried crust.>Assess start zones carefully and use safe travel techniques.>Be alert to conditions that change with elevation, especially if you venture into the alpine.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 5

Wind Slabs

An icon showing Wind Slabs
Recent winds have dominated alpine areas. Wind slabs are likely found lee of terrain features.
Use caution in lee areas in the alpine. Recent wind loading have created wind slabs.>Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.>

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Nov 23rd, 2013 2:00PM