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Archived

Avalanche Forecast

Jan 28th, 2017–Jan 29th, 2017
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
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
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Northwest Inland.

A storm has ramped up avalanche danger in the region, particularly in areas that have seen more than 20 cm of new snow. Deeper in the snowpack, the added load will test persistent weak layers.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Sunday: Mainly cloudy with isolated flurries and a trace of new snow. Winds strong from the southwest. Freezing level to 900 metres with alpine temperatures of -4. Monday: A mix of sun and cloud. Winds moderate to strong from the northwest. Freezing level returning to valley bottom with alpine temperatures around -11. Tuesday: A mix of sun and cloud. Winds light from the north. Alpine temperatures of -13.

Avalanche Summary

Stormy weather has been obscuring visibility of higher elevation avalanche terrain, but warm valley temperatures have allowed numerous loose wet avalanches to be observed occurring at lower elevations. Reports from earlier in the week included a few avalanches up to size 3.0  remotely triggered in the Kispiox area on Monday on south through west aspects at 1700-1800 metres. These avalanches were about 80 cm deep and are suspected to have released on the December 25th surface hoar. Aside from new storm slabs being formed and becoming a problem in their own right, it should be noted that these slabs are introducing a new load above our deeper snowpack weaknesses, increasing their likelihood of triggering.

Snowpack Summary

Stormy weather over Friday and Saturday has delivered anywhere from 10-25 cm of new snow to the region. Including snow from earlier in the week, 15-50 cm of storm snow now sits above a widespread rain crust up to about 1300 m. At treeline and above, the storm snow overlies wind slabs recently formed on lee and cross loaded features. Ongoing snowfall has effectively shifted this wind slab problem into a more generalized storm slab issue. Below our the storm snow forming the upper snowpack, several buried surface hoar layers can be expected roughly 35-75 cm deep. These layers have recently yielded moderate to hard results in snowpack tests. Many areas have hard slabs in the upper snowpack above weak sugary snow near the ground. Triggering a deep persistent slab above this sugary snow will remain a low probability high consequence scenario for some time, with probability increasing as new snow and strong winds add load to the snowpack. Snow profile information from Tuesday at Hankin reported 110cm at treeline with a buried surface hoar layer down 25 cm and weak facetted snow down 75 cm as well as depth hoar above the ground. You can see the full report on the MIN.

Avalanche Problems

Deep Persistent Slabs

New snow and wind are adding load to weak, sugary snow at the bottom of the snowpack and potential exists for full depth avalanches. This problem may be more likely in shallow snowpack areas near Kispiox and in the north of the region.
Avoid areas with overhead hazard.Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 3

Storm Slabs

New snow and strong winds have formed a fresh storm slab problem. Avalanche likelihood and size has increased with each pulse of snow and wind and danger will remain elevated as the storm breaks on Sunday.
If triggered the storm slabs may step down to deeper layers resulting in large avalanches.Take extra caution in lee areas. Recent snowfall and wind loading has created storm slabs.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 3