Avalanche Forecast
Issued: Jan 6th, 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.
wlewis,
Avalanche Canada
The song remains the same.
Conservative terrain selection is the best management for tricky persistent layers. Be wary of rocky start zones where the snowpack varies from thick to to thin. Weak layers are more easily triggered here.
Check out the new Forecasters' Blog for more details on managing our challenging snowpack.
Summary
Confidence
Avalanche Summary
Persistent slabs and deep persistent slabs continue to be reported throughout the region, naturally and human triggered to size 3. Avalanches are failing on the weak layers described in the Snowpack Summary, from 70 cm and up to 200 cm deep in wind affected terrain. Activity has been reported on all aspects, mostly between 1800 and 2500 m elevation. Recent MIN reports showcase conditions well: check out Joss Mountain, & North McCrea Mt MINS.
These avalanches continue to indicate that these buried weak layers remain reactive, and capable of producing large consequential avalanches. Conditions will continue to be tricky for a while - many of these human-triggered avalanches were a surprise to the individuals triggering them.
Small slabs in wind loaded features have also been triggered by riders, which have the potential of stepping down to the deeper weak layers.
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 in the mid and lower snowpack continue to be a concern, with large and surprising (remote or accidentally 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 ground.
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
Friday Night
Cloudy with possible flurries. Moderate southwest wind. Freezing level drop to 500 m.
Saturday
Cloudy with light snowfall, accumulation 2 to 5 cm. Moderate southerly wind. Alpine high of -3 °C. Freezing levels 800-1000 m.
Sunday
Cloudy with light snowfall, accumulations up to 2 cm. Moderate southerly wind. Alpine high of -3 °C. Freezing levels 800-1000 m.
Monday
Cloudy with light snowfall, accumulations up to 5 cm. Moderate southerly wind. Alpine high of -3 °C. Freezing levels 800-1000 m.
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. This layer has been most problematic around treeline and lower alpine elevations and has produced 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 north facing 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 7th, 2023 4:00PM
