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Archived

Avalanche Forecast

Jan 28th, 2016–Jan 29th, 2016
Alpine
4: High
The avalanche danger rating in the alpine will be high
Treeline
4: High
The avalanche danger rating at treeline will be high
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: Northwest Coastal.

Give the snowpack time to adjust to the load from recent heavy snow and rain. Conservative terrain selection is still critical.

Confidence

Moderate

Weather Forecast

On Friday expect 5-15cm on new snow, strong southerly winds and freezing levels at about 800m. On Saturday, the region will see another 5cm of new snow with mainly overcast skies forecast for Sunday. Winds for the weekend will be mainly light from the north while freezing levels hover around 500m.

Avalanche Summary

In recent days observations were limited due to stormy weather; however, professional operators in the region were still reporting fairly widespread explosive and naturally triggered large storm and persistent slab avalanches. Many of the avalanches were suspected to have failed on the January 9th surface hoar. Forecast cooling and should help gradually reduce natural avalanche activity. But, for the short term storm slabs will likely remain sensitive to light loads, while potential remains for very large persistent slab avalanche activity.

Snowpack Summary

A warm, wet and windy storm has formed deep, dense and reactive storm slabs at higher elevations while rain has saturated the snowpack below treeline. The snow line fluctuated a great deal during the storm which dropped around 80mm of precipitation in the Terrace area (and slightly less in the mountains around Stewart) over the past 4 days. The January 9th surface hoar/facet layer is down 70-150 cm in most places, and is a concern on all aspects and elevations. Around the same depth you may also find a surface hoar/facet interface from around New Years. The hope is the combination of heavy storm loading and warm temperatures will have flushed out these weak layers in many areas, but that remains to be seen. In the wake of the storm, there will be a lot of uncertainty regarding the reactivity and distribution of this destructive persistent avalanche problem. Additionally, the snowpack will require time to adjust to the stress of heavy storm loading. A very conservative approach to mountain travel is still required.

Avalanche Problems

Persistent Slabs

Deep and destructive persistent slab avalanches will remain a concern in many places as the snowpack adjusts to recent heavy storm loading.
Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Be careful with low angle slopes that may not normally be a concern.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 3 - 6

Storm Slabs

Deep and dense storm slabs are are expected to remain sensitive to light loads. Watch for increased reactivity in wind-exposed terrain.
Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Be alert to conditions that change with elevation.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely

Expected Size: 1 - 4