Avalanche Forecast

Issued: Feb 10th, 2019 5:34PM

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

cgarritty, Avalanche Canada

North Columbia.

Dangerous avalanche conditions persist in the North Columbia. This continues to be the most active region in British Columbia for persistent slab avalanches. Seek out simple terrain and low consequence slopes.

Summary

Confidence

High -

Weather Forecast

Sunday night: Cloudy with clear periods. Light southwest winds. Monday: A mix of sun and cloud. Light southwest winds. Alpine high temperatures around -19.Tuesday: Cloudy with sunny periods. Light southeast winds, shifting to southwest in the alpine. Alpine high temperatures around -15.Wednesday: Cloudy with sunny 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. The avalanche was triggered by the rider at 2100 metres on a south aspect. The crown fracture was 15-100 cm deep, suggesting wind loading was a factor in the incident. The avalanche measured 40 metres wide and ran 300 metres.On Friday a natural size 2 wind slab avalanche was observed on an east facing aspect near 3000 m. Strong to extreme wind Friday night into Saturday may have initiated a natural wind slab avalanche cycle. The North Columbias are the hotspot for human triggered persistent slab avalanches as a weak layer that was buried in mid January continues to be sensitive to human triggers. This layer is touchy enough for avalanches to be triggered remotely (from a distance). Skier and snowmobile triggered avalanches from size 1.5-2.5 have been reported on all aspects at and below treeline almost every day for the last two weeks. The bulk of this activity is occurring below 1900 m. This MIN report from Monday does a great job of illustrating the sensitivity of this weak layer.

Snowpack Summary

30-80 cm of recent new snow sits on surface hoar (feathery crystals), facets (sugary snow), wind slabs and a crust on sun-exposed slopes. In many areas, recent winds have redistributed the new snow, forming wind slabs on all aspects due to shifting wind directions.The most notable feature in the snowpack at this time is a persistent weak layer that was buried in mid January, which is now buried 50-100 cm. This layer consists primarily of surface hoar, however there is also a crust associated with it on sun-exposed slopes. This layer is the most prominent at treeline and below, and continues to produce large avalanches.

Problems

Persistent Slabs

50-100 cm of snow sits above a weak layer of surface hoar (feathery crystals) and crust. This layer continues to be reactive to human triggers. The trees are not a safe haven right now, in fact treeline may be the most dangerous elevation band.

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

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Possible

Expected Size

1.5 - 2.5

Wind Slabs

30-80 cm of old storm snow continues to be redistributed by arctic wind out of the north and east. Wind slabs forming at treeline have the potential to step down to the buried surface hoar resulting in large avalanches.

Avoid freshly wind loaded features.If triggered, wind slabs may step down to deeper layers and result in even larger avalanches.Wind from a variety of directions has formed wind slabs in unusual locations at and above treeline.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

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