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Avalanche Forecast

Archived

Feb 8th, 2020–Feb 9th, 2020

Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches unlikely, human triggered possible.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely.

Regions

South Coast Inland.

Friday's storm delivered 20-30 cm in the south of the region and 10-15 cm in the north with changing wind direction from southwest to north. Wind slabs were created on all aspects and might still be sensitive to human triggers especially when hit by the sun. 

Confidence

Moderate - Uncertainty is due to the limited number of field observations.

Weather Forecast

Saturday Night: Clear, light to moderate northwest wind, alpine high -12 C, freezing level at valley bottom.

Sunday: Mix of sun and cloud, light to moderate northwest wind, alpine high -8 C, freezing level 1000 m.

Monday: Mostly sunny, light to moderate northwest wind, alpine high -5 C, freezing level 1500 m.

Tuesday: Mostly cloudy, light to moderate southwest wind, alpine high -5 C, freezing level 1000 m.

Avalanche Summary

No new avalanches were reported on Thursday and Friday.

On Wednesday numerous small (size 1) natural slab avalanches were observed below treeline which released within the recent storm snow and were very soft. Several small (size 1) and one large (size 2) loose dry avalanche were reported. 

The deep persistent slab avalanche activity observed during last weekend's storm in the northern portion of the region seems to have tapered off. Although the likelihood of triggering has reduced there is still concern for deep releases in that part of the region.

Snowpack Summary

Friday's storm delivered 20-30 cm in the south of the region and 10-15 cm in the north. Strong southerly wind during the storm shifted to northerly wind and created wind slabs on all aspects. The snow surface is wind affected at treeline and in the alpine. The recent storm snow sits on a rain crust below 1900 m.

In the north part of the region (ie. Goldbridge/Duffey/Hurley), a few deep instabilities exist in the snowpack, including a weak basal facet crust complex. This has been the failure plane in ongoing reports of very large, deep persistent avalanches.

The south of the region, including the Coquihalla and Manning areas, currently have no concerns about deeply buried weak layers.

Terrain and Travel

  • Recent wind has varied in direction so watch for wind slabs on all aspects.
  • Be especially cautious as you transition into wind affected terrain.
  • Be alert to conditions that change with elevation.

Problems

Storm Slabs

Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.

Deep Persistent Slabs

Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.