Avalanche Forecast
New snow and wind are creating very dangerous conditions. It's a good time to avoid avalanche terrain. Touchy storm slabs exist at all elevations. A small avalanche could step down to deeper weak layers.
Confidence
High
Avalanche Summary
On Thursday a widespread natural avalanche cycle was reported in Pine Pass and we suspect across the region.
Looking forward, natural and rider-triggered storm and wind slab avalanches are likely as we receive new snow and strong wind through the forecast period. Smaller avalanches could step down to the facets near the base of the snowpack, producing very large avalanches. See more on the potential of triggering deeper weak layers Forecasters' Blog.
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Snowpack Summary
Up to 30 cm of new snow (with a bunch more expected overnight Thursday and into Friday) accompanied by strong to extreme westerly winds has formed widespread reactive storm slabs. The snow sits on previously wind-affected snow. Below this, a melt-freeze crust is found on sun-exposed slopes and everywhere below 1600 m.
Several crust/facet/surface hoar layers exist in the upper and middle portions of the snowpack. Recent observations suggest these layers are not as concerning as in neighbouring regions.
The most concerning layer is at the base of the snowpack from large and weak facets formed in November. This layer is widespread and most likely problematic in steep, rocky alpine terrain.
Weather Summary
Thursday Night
Cloudy new snow 10-20+ cm. Ridgetop wind 70-100 km/h from the southwest. Treeline temperatures steady -8°C.
Friday
Cloudy with snowfall, accumulation of 10-20 cm by late afternoon with higher amounts on the western slopes of the region. Ridgetop wind 50-80 km/h from the west and treeline temperature -8°C. Freezing levels 1300 m.
SaturdayCloudy with snowfall, accumulation 5-10 cm. Ridgetop wind 40-60 km/ h from the southwest. Treeline temperature -6 °C. Freezing level 1500 m.
SundayCloudy with snowfall, accumulation 5 to 10 cm. Ridgetop wind 30-50 km/h from the southwest and treeline temperature -5 °C. Freezing level 1500 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.
- Avoid exposure to overhead avalanche terrain, avalanches may run surprisingly far.
- Storm slab size and sensitivity to triggering will likely increase through the day.
- Be aware of the potential for large, destructive avalanches due to the presence of deeply buried weak layers.
Avalanche Problems
Storm Slabs
New snow and strong to extreme southwest wind will build reactive storm slabs through the forecast period. Storm and wind slab avalanches may step-down to deeper weak layers initiating large and destructive avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Very Likely - Certain
Expected Size: 1 - 2.5
Deep Persistent Slabs
A layer of large and weak facets sits near the base of the snowpack. This layer is most prominent in upper treeline and lower alpine elevations. Storm slab avalanches could step down to this layer initiating very large avalanches. Riders are most likely to trigger an avalanche on this layer in steep, shallow terrain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 2 - 3.5