Avalanche Forecast
Issued: Feb 5th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Deep Persistent Slabs and Persistent Slabs.
lbaker,
Avalanche Canada
With additional snow arriving Monday afternoon, we expect dangerous avalanche conditions to persist. Human-triggered avalanches are likely on steep slopes and natural avalanches will likely continue on wind-loaded slopes. Storm slab avalanches could step down to the facets near the base of the snowpack, producing very large avalanches.
Summary
Confidence
Moderate
Avalanche Summary
In the Pine Pass area, heavy snowfall caused a natural avalanche cycle that started on Thursday and continued through the weekend. Reports from Thursday indicate storm slabs were very reactive to snowmobile traffic, producing many size 1 to 1.5 storm slab avalanches that propagated widely. On Saturday, explosives control produced several size 2 to 3 wind slab avalanches in cross-loaded alpine start zones.
See more on the potential of triggering deeper weak layers in our latest Forecasters' Blog.
Snowpack Summary
Stormy weather over the past week has brought 40 to 80 cm of new snow to the region. Warm windy weather is causing storm snow to settle into reactive slabs. The storm 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 gaining strength, but remain on our radar as active loading continues.
The most concerning persistent weak 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 and upper treeline terrain.
Weather Summary
Sunday Night
Mainly cloudy with clear periods and isolated flurries, trace accumulation. Alpine temperatures reach a low of -6 C. Ridge wind westerly 30-50 km/h. Freezing levels fell from 1500 m to 500 m.
Monday
Mainly cloudy with scattered flurries becoming hevy in the afternoon. 2-8 cm accumulation. Alpine temperatures rise to -4 C. Ridge wind southwest 40-60 km/h. Freezing level rises to 1400 meters.
Overnight 5-10 cm accumulation, up to 20 cm in localized areas.
Tuesday
Clear with cloudy periods and isolated flurries, trace cm accumulation. Alpine temperatures drop to -6 C. Ridge wind west 10-30 km/h. Freezing level drops to 1000 meters.
Wednesday
Mix of sun and cloud with the possibility of light flurries, 2-5 cm accumulation. Alpine temperatures rise to -7 C. Ridge wind southwest 40-60 km/h. Freezing level rises to 800 meters.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Expect slab conditions to change drastically as you move into wind exposed terrain.
- Watch for rapidly changing conditions during periods of heavy loading from new snow, wind, or rain.
- Avoid exposure to overhead avalanche terrain, avalanches may run surprisingly far.
Problems
Storm Slabs
An additional 5 -15 cm of snow and strong southwesterly winds continue to build reactive storm slabs. There is ample evidence that storm snow is not bonding well to surfaces below and is primed for human triggering. Storm and wind slab avalanches may step-down to deeper weak layers and initiate large and destructive avalanches.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
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
Expected Size
Persistent Slabs
Numerous problematic weak layers exist in the top meter of the snowpack. Recent observations suggest these layers are gaining strength, but we would continue to be cautious around steep openings within and near treeline elevations as active loading continues.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 6th, 2023 4:00PM
