Avalanche Forecast
Issued: Jan 5th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Deep Persistent Slabs and Wind Slabs.
mconlan,
Avalanche Canada
Buried weak layers continue to produce large, unnerving avalanches. Disciplined terrain travel is warranted. Read about how this year's snowpack is different in our Forecasters' blog.
Summary
Confidence
Moderate
Avalanche Summary
Numerous large to very large (size 2 to 3) avalanches have been naturally and human triggered over the last week, failing on the weak layers described in the Snowpack Summary, 70 to 200 cm deep. Activity was mostly reported between 1800 m and 2500 m elevation and on all aspects. Check out this recent MIN.
These avalanches continue to indicate that these buried weak layers remain reactive, and are capable of producing large consequential avalanches. Many of these human-triggered avalanches were a surprise to the individuals triggering them.
Small wind slabs have also been triggered by riders, which have the potential of stepping down to the deeper weak layers.
Please continue to share any observations or photos on the Mountain Information Network.
Snowpack Summary
30 to 50 cm of soft snow is on the snow surface in areas sheltered from the wind. Wind slabs are forming in lee terrain features from strong southerly wind in wind-exposed terrain. New wind slabs may sit over a layer of surface hoar and/or crust.
The upper snowpack is generally settled and well-bonded, however buried weak layers continue to be a concern, with large and surprising (remote or accidental triggered) avalanche activity reported throughout the last week.
A weak layer of crust, facets and/or surface hoar buried just before Christmas is buried 40 to 70 cm deep. The lower snowpack is generally weak and facetted with a weak layer of large facets from mid-November found near the bottom.
Snowpack depths are roughly 150 to 200 cm at treeline. This year's snowpack is weaker than usual, as described in our Forecasters' blog.
Weather Summary
Thursday Night
Cloudy with light snowfall, accumulation 2 to 5 cm. Moderate to strong southwest winds. Alpine high of -5 °C.
Friday
Cloudy with light snowfall, accumulation 1 to 3 cm. Moderate southwest wind. Freezing level around 900 m. Alpine high of -6 °C.
Saturday
Cloudy with light snowfall, accumulation 2 to 5 cm. Moderate southerly wind. Alpine high of -6 °C.
Sunday
Cloudy with light snowfall, accumulation 2 to 5 cm. Moderate southerly wind. Alpine high of -6 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Problems
Persistent Slabs
A layer of surface hoar, facets and/or a crust may be found around 40 to 70 cm deep, which is a prime depth for human triggering. To date this layer has been most problematic around treeline and lower alpine elevations and has formed large 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 has most recently been problematic in lower alpine elevations. Riders are most likely to trigger it in terrain with shallow, variable snow depths. Shallower avalanches could also step down to this layer, producing a very large and consequential avalanche.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Southerly wind is forming new wind slabs in lee terrain features. Avalanches triggered in wind-loaded terrain have the potential to step down to deeper weak layers, creating larger than expected avalanches.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 6th, 2023 4:00PM
