Avalanche Forecast

Issued: Feb 13th, 2019 4:44PM

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

Avalanche Canada mbender, Avalanche Canada

The likelihood of triggering a persistent slab has reduced, however the consequence of doing so would be significant.

Summary

Confidence

High -

Weather Forecast

WEDNESDAY Night: Clear periods, light south wind, alpine temperature -13 C.THURSDAY: Mix of sun and cloud, light southeast wind, alpine temperature -10 C.FRIDAY: Flurries, accumulation 5 cm , light to moderate southwest wind, alpine temperature -8 CSATURDAY: Cloudy with isolated flurries, light north wind, alpine temperature -12 C

Avalanche Summary

On Tuesday there was report of a skier triggered size 2 persistent slab avalanche 60 cm deep on an east aspect at 1900m. On Sunday there was a small human-triggered avalanche was reported from a north aspect at 2100 m. It failed around 35 cm deep on the mid-January surface hoar layer. A snowmobiler died in a large (size 2) slab avalanche on Saturday just outside this region in the North Columbias (report here). The avalanche was triggered by the rider at 2100 m on a south aspect. The crown fracture varied from 15-100 cm deep, suggesting wind loading was a factor in the incident.

Snowpack Summary

A touchy weak layer responsible for a several close calls and surprise avalanches lies approximately 50 cm below the surface (30 cm in shallow areas, 60 cm or more in deeper spots). This weak layer was buried mid-January and comprises a mix of surface hoar and facets. On southerly aspects, it lies on top of a sun crust. This is a dangerous weak layer that is shallow enough to be easily triggered but deep enough to produce large avalanches. It is most prevalent at treeline and below treeline elevations, but there have been a few reports of its presence in sheltered areas in the alpine.Strong northerly and easterly winds have created complicated patterns of wind-loaded snow.Average snow depths are approximately 270 cm. Lower layers in the snowpack are not a significant factor at this time.

Problems

Persistent Slabs

An icon showing Persistent Slabs
Approximately 50 cm of snow sits above a persistent weak layer of surface hoar and crust that was buried in mid-January. This layer continues to be reactive to human triggering.
Any steep opening in the trees should be treated as suspect right now.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

An icon showing Wind Slabs
Many locations have been hit hard by winds over the last week forming wind slabs in the lee of terrain features on a variety of aspects. There is potential for a wind slab avalanche to step-down to a persistent weak layer below.
If triggered, wind slabs may step down to deeper layers and result in even larger avalanches.Avoid areas where the snow feels stiff and/or slabby.Back off if you encounter whumpfing, hollow sounds, or shooting cracks.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Feb 14th, 2019 2:00PM

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