Avalanche Forecast
Regions: Dogtooth, East Purcell, Purcells, St. Mary, West Purcell.
There is some uncertainty in the intensity of the incoming weather and it's impact on the snowpack. Make conservative terrain choices and consider the consequences of being wrong.
Confidence
Low
Avalanche Summary
On Monday evening we received reports of a fatal avalanche accident. This Avalanche occurred on a west facing slope at treeline in the southern Selkirk mountains. This avalanche did not occurre in this forecast region but similar snowpack conditions exist in the Purcells. This MIN report has more details.
On Tuesday a few small wind slab avalanches were observed in north facing alpine. No significant avalanches were observed on Wednesday.
Please continue to share any observations or photos on the Mountain Information Network.
Snowpack Summary
New wind slabs can likely be found on exposed treeline and alpine terrain on north and east facing slopes. As the freezing level rises the surface will likely become moist at lower elevations.
A new surface hoar layer can be found just below the surface as well as a crust on some steep south facing slopes and all aspects below treeline.
The upper snowpack continues to settle. The mid and lower snowpack is generally weak and faceted, with a number of weak layers. Of significant concern is a layer down 30 to 50 cm from the surface consisting of a crust, facets, and/or surface hoar. And a layer of large facets and a crust down roughly 50 to 110 cm from the surface. The snow below this deeper weak layer is unconsolidated and weak.
Snowpack depths remain highly variable, ranging from 60 to 150 cm at treeline. In General the snowpack is shallow and weak.
Weather Summary
Thursday Night
Cloudy with flurries bringing a few centimeters of new snow. Strong southerly winds. Possible temperature inversion with a overnight high of -2 at 2000m.
Friday
Stormy with up to 10cm of new snow expected at treeline and above. Rain or freezing rain at lower elevations. Warm air aloft with temperatures around -2 at 2000m. Moderate to strong southerly winds.
Saturday
Cloudy with flurries bringing up to 5cm of new snow. Light southerly winds and freezing levels around 1500m.
Sunday
Cloudy with flurries bringing trace amounts of new snow. Light southerly winds and a high of -3 at 2000m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Uncertainty is best managed through conservative terrain choices at this time.
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
- Be especially cautious as you transition into wind affected terrain.
Avalanche Problems
Deep Persistent Slabs
A weak layer near the base of the snowpack, buried in November, remains a concern despite lack of recent avalanche activity. Human triggering of this layer remains possible, especially in shallow areas with variable snow depths.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Unlikely - Possible
Expected Size: 2 - 3.5
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. Of more concern at the treeline elevations and below.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Unlikely - Possible
Expected Size: 1 - 2.5
Wind Slabs
New wind slabs will likely form throughout the day on north and east aspects.
Be aware that wind slabs can step down to deeper layers.
Aspects: North, North East, East, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2