Archived

Avalanche Forecast

Feb 12th, 2015–Feb 13th, 2015

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

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: Banff Yoho Kootenay.

Natural activity is tapering, but conditions are still prime for human triggering. Conservative terrain selection is a must as we transition out of a large avalanche cycle.

Weather Forecast

Continued warm temperatures with freezing levels around 2000m until Saturday AM. The winds have picked up from the west and are forecasted to be in the moderate to strong range at ridgetop until Saturday PM. A small bout of precipitation (5mm) on Friday overnight, but otherwise partly cloudy skies with a clearing trend Saturday AM.

Snowpack Summary

45-70 cm of storm snow overlies either a rain crust or facets from January 30th. This snow combined with warm temperatures has created storm and wind slabs overlying the Jan. 30th interface. The basal facet/depth hoar layers are still active in shallow snowpack areas. Little recovery overnight created isothermal conditions below 1800m today.

Avalanche Summary

Natural avalanche activity is tapering as the snowpack slowly adjusts to the new load. However, moderate to hard sudden collapse snowpack tests today in the Bow Summit area indicate skier triggering is still very possible.

Confidence

Avalanche Problems

Storm Slabs

50 to 90 cm of storm snow exist on the January 30th interface which is a crust below 2000m and facets above. A poor bond exists at this interface and large avalanches have been observed running on this layer. Wide propagations are still possible.

If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 2 - 3

Wind Slabs

Recent winds have created wind slabs in the lee of alpine features.

Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 2 - 3

Deep Persistent Slabs

The base of the snowpack remains weak due to basal depth hoar/facets. Initiation of a wind slab or a storm slab may step down to trigger large avalanches in thin snowpack areas.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 2 - 3