Avalanche Forecast
Issued: Dec 17th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
wlewis,
Avalanche Canada
Danger ratings have decreased but concern still remains for deeper weak layers and lingering wind loaded features.
A deep persistent slab problem is present, which is uncommon for this region. Good travel habits and conservative terrain choices are tools to manage this problem.
Summary
Confidence
Moderate
Avalanche Summary
As northerly winds are expected to continue to redistribute snow, rider triggered wind slabs remain possible.
On Monday near Pemberton, a skier-triggered persistent slab avalanche occurred on a northwest aspect in the alpine, on a crust and surface hoar layer. This avalanche triggered a size 2 on a nearby slope, on facets and depth hoar near the ground level. Settlements (a sign of instability) have been reported in shallow and rocky features where weak layers sit shallower and closer to the surface.
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Snowpack Summary
In exposed terrain at higher elevations, pockets of wind slab sit in wind loaded features. Strong winds have pushed this snow into features lower on slopes than typically seen. Large surface hoar has been reported on the surface in sheltered areas, with a crust present on solar aspects.
Two weak layers of concern sit in the snowpack:
A layer of surface hoar from early December is buried 20-40 cm deep. This layer can be found in sheltered and shaded terrain features.
The mid and lower snowpack consist of crusts and facet layers, with depth hoar observed near the ground, which is very weak and highly uncommon for this region.
The snowpack is currently weak and shallow for mid December. In deeper areas, snowpack depths only reach 100-130 cm.
Weather Summary
An Arctic front dominates the weather over BC. Light snowfall is expected Saturday night as a low south of Vancouver Island briefly competes with the cold air.
Saturday Night
Mostly cloudy with 5 cm of snow possible. Moderate southwesterly winds continue. Freezing level below valley bottom.
Sunday
A mostly cloudy with a trace to 3 cm of snow possible. Moderate westerly winds continue at ridgetop. Temperatures drop further, with alpine highs of -22°C.
Monday
Clearing skies with moderate to strong westerly winds. Freezing level below valley bottom. Alpine high of -24 °C.
Tuesday
Cloudy skies with moderate to strong westerly winds. Light snowfall. Freezing level below valley bottom, alpine high of -20 °C.
MondayMore details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid freshly wind loaded terrain features.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Conditions may have improved, but be mindful that deep instabilities are still present.
Problems
Wind Slabs
Wind slabs formed earlier in the week may still be reactive to human triggers. Small but reactive new wind slabs are likely form with snowfall overnight Saturday and into Sunday. Expect to find wind loading on all aspects as winds switch from north to southwest. Slabs may be poorly bonded to the crust below.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Weak crystals sit at the base the snowpack creating concern for large avalanches.
Whumpfing and cracking have been observed and human triggering should be considered possible on any steep slopes where snow becomes denser and forms a slab of cohesive snow - like wind affected slopes.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 18th, 2022 4:00PM
