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Archived

Avalanche Forecast

Feb 12th, 2018–Feb 13th, 2018
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: Kootenay Boundary.

Watch for new wind slabs distributed across a wide range of aspects and elevations. A cornice or wind slab release would be one of the most effective ways to trigger a deeply buried weak layer.

Confidence

High -

Weather Forecast

Tuesday: Cloudy with flurries beginning in the afternoon and bringing approximately 10 cm of new snow by Wednesday morning. Light to moderate northwest winds, strong in the alpine and increasing overnight. Alpine high temperatures to around -5 under a lingering temperature inversion. Cooling at lower elevations.Wednesday: Mainly cloudy with lingering isolated flurries and a trace to 5 cm of new snow. Light to moderate northwest winds. Alpine high temperatures around -9.Thursday: A mix of sun and cloud. Light to moderate southwest winds. Alpine high temperatures of -10.

Avalanche Summary

A widespread avalanche cycle occurred this week on all aspects and elevations. Persistent slabs up to size 3 were observed during the peak of the storm loading on Thursday. On Friday and Saturday, natural activity slowed down, but large explosive and machine-triggered avalanches continued to be reported.The natural cycle has wound down, but human-triggering remains a real concern. You might be surprised by how large an avalanche can be triggered and how far it could run.

Snowpack Summary

Storm snow accumulations from the past week vary from 10-45cm across the region at upper elevations. In the alpine this new snow has been redistributed to leeward slopes from strong northwest winds. Fragile cornices may be found at ridge top. Below 1850 m, around 5 cm of low density snow covers a hard crust. We now have 1- 2 m of settled snow sitting on three significant surface hoar/crust layers that were formed early to mid-January, and back in December. Near the base of the snowpack a crust/ facet interface exists that will likely haunt us all season. These persistent weak layers that lurk within the snowpack have produced large and destructive avalanches. Although this activity has been diminishing gradually, recent activity and continued sudden snowpack test results have kept them a top concern in the region.The complex and widespread nature of our multiple overlapping persistent slab problems continues to demand respect and diligence from backcountry travelers in the region.

Avalanche Problems

Wind Slabs

Recent strong and variable winds have redistributed loose snow into new wind slabs and fragile cornice growth on a variety of aspects.
If triggered, wind slabs or cornices may step down to deeper layers and result in large avalanches.Watch for patterns of recent wind loading and avoid areas where the surface is stiff or slabby.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 2.5

Persistent Slabs

Several deeply buried weak layers exist in the snowpack. Although the likelihood of triggering a persistent slab is gradually decreasing, the consequences remain very high.
Avoid lingering in runout zones.Avoid steep convexities or areas with a thin or variable snowpack.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Possible

Expected Size: 2 - 4