Avalanche Forecast

Issued: Feb 10th, 2019 5:32PM

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

cgarritty, Avalanche Canada

Cariboos.

Wind slabs have kept avalanche danger heightened at upper elevations and our persistent slab problem will be slow to heal. Conservative terrain selection remains paramount.

Summary

Confidence

Moderate -

Weather Forecast

Sunday night: Mainly clear. Light northeast winds, closer to southeast in the alpine.Monday: Sunny with cloudy periods. Light variable winds. Alpine high temperatures around -20.Tuesday: A mix of sun and cloud with isolated flurries and a trace of new snow. Light southeast winds. Alpine high temperatures around -16.Wednesday: Sunny with cloudy periods. Light northeast winds. Alpine high temperatures around -11.

Avalanche Summary

A snowmobiler was fatally involved in a large (size 2) slab avalanche on Saturday in the Oventop Creek area in the Bone Creek drainage. This is in the adjacent North Columbia region. The avalanche was triggered by the rider at 2100 metres on a south aspect. The crown fracture was 15-100 cm deep by 40 metres wide and the avalanche ran 300 metres.On Friday avalanches failed on the mid-January surface hoar to size 1 on north and northeast facing slopes between 1700 and 2000 m. The persistent weak layer that was buried in mid January continues to be reactive to human triggers. Human triggered avalanches up to size 2.5 have been reported almost everyday in the last week. This layer is sensitive enough for avalanches to be triggered remotely (from a distance). This layer has been the most reactive at treeline and below, although there have been a few reports of its presence in isolated sheltered areas in the alpine. Click here to see a Mountain Information Network post that described conditions in Allen Creek on Wednesday.Strong to extreme north, northeast and east wind over the last 72 hours has created wind slabs that may remain sensitive to human triggering in wind exposed features.

Snowpack Summary

30-60 cm of old storm snow is sitting on surface hoar (feathery crystals), facets (sugary snow) and a crust on sun-exposed slopes. In many areas, recent strong winds have redistributed the new snow and formed wind slabs on all aspects due to shifting wind directions.The most notable feature in the snowpack is a persistent weak layer that was buried in mid January, which is now 50-80 cm below the surface. This layer consists of surface hoar and a crust on sun-exposed slopes. It is most prominent at treeline and below, and continues to produce avalanches.

Problems

Wind Slabs

Many locations have been hit hard by winds over the last few days forming wind slabs in the lee of terrain features on a variety of aspects. Strong to extreme wind out of the north, northeast and east has likely formed slabs in unusual locations.

Back off if you encounter whumpfing, hollow sounds, or shooting cracks.Avoid areas where the snow feels stiff and/or slabby.If triggered, wind slabs may step down to deeper layers and result in even larger avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

50-80 cm of snow sits above a weak layer of surface hoar and crust that was buried in mid January. This layer continues to be reactive to human triggering. The trees are not a safe haven this weekend.

Avoid convexities as well as steep, open and/or sparsely treed slopes at and below treeline.Use conservative route selection, choose moderate angled and supported terrain with low consequence.Any steep opening in the trees should be treated as suspect right now.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

1.5 - 3

Valid until: Feb 11th, 2019 2:00PM