Avalanche Forecast
Regions: Dogtooth, East Purcell, Moyie, Purcells, St. Mary.
Loose surface snow and light snowfall over the day brings potential for fresh wind slab development.
Plan your backcountry trips with the short and very cold days in mind.
Confidence
Moderate
Avalanche Summary
On Tuesday and Wednesday explosive control in the region produced small avalanches with a depth of 10cm.
Although avalanche activity has tapered off, weak layers still exist in the snowpack that may react to human triggers.
If you are headed into the backcountry please consider filling out a Mountain Information Network report.
Snowpack Summary
Southwest winds continue to move snow (where available as fresh snow or loose surface snow) into wind slabs on north and east facing terrain features. Wind slabs sit over a a layer of facets and surface hoar increasing reactivity.
The main layer of concern is the mid-November layer, which is made up of either surface hoar, facets, or crusts buried 40 to 80 cm deep. Avalanche activity on this layer has tapered off but it could still be possible to trigger this layer in isolated terrain features near treeline.
Alpine snowpack distribution is variable, with depths ranging from 70 to 140 cm.
Weather Summary
Cold arctic air begins to weaken on Saturday, as a warm Pacific low pushes light snowfall and strong winds into the interior this week.
Friday Night
Cloudy with trace amounts of new snow expected. Strong southwesterly winds. Freezing level below valley bottom.
Saturday
Cloudy with flurries bringing up to 5cm of new snow. Strong southwest winds and a high of -20°C.
Sunday
Mostly cloudy with flurries bringing trace amounts of new snow. Moderate southwest winds and a high of -15°C.
Monday
A mix of sun and cloud with trace amounts of snow possible. Moderate southwest winds. Freezing levels rise to 800 m. High temperatures of -5°C expected.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- 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.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
Avalanche Problems
Wind Slabs
Strong southwest winds will likely continue to form wind slabs in exposed terrain at treeline and above. These slabs will be found on east and north facing slopes sitting above facets and surface hoar, increasing reactivity and propagation.
Strong winds can move snow further down slope, look for wind loading in mid slope terrain features where wind may slow and deposit snow. Wind slab avalanches could step down to deeper layers.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2
Persistent Slabs
A layer of surface hoar, facets and, a crust from mid November is buried around 40-80 cm deep. This layer has become hard to trigger but could still be sensitive to rider traffic on isolated slopes at treeline and below where the snow above feels stiff, slabby and consolidated.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Unlikely
Expected Size: 1.5 - 2.5