Avalanche Forecast
Issued: Jan 11th, 2024 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Storm Slabs and Deep Persistent Slabs.
dsaly,
Avalanche Canada
The arctic air is here. Dial back trip plans to easier, shorter days and watch for unusual wind loading patterns from north winds. See our Forecasters' Blog for more on managing the cold.
Summary
Confidence
Avalanche Summary
Wednesday avalanche reports documented a natural storm slab cycle averaging size 1-2, with a few size 2.5 avalanches. During the day, storm snow was very reactive to rider traffic including a size 1.5 avalanche, 70 cm deep, remotely triggered by skiers on a treeline ridge above the slope. Most slab avalanches were 50-70 cm deep and many reportedly ran on a layer of surface hoar buried Jan 4.
Snowpack Summary
Roughly 30-40 cm of new snow fell in the region Monday night through Tuesday. It buried moderately wind-affected snow in exposed areas at higher elevations and otherwise added to about 50 cm of recent storm snow. All this snow collectively overlies a variety of old surfaces, but sheltered terrain where it may overlie preserved surface hoar is the most concerning. It overlies a crust below about 1600 m.
Two additional surface hoar layers in the top 2 m of the snowpack are diminishing in importance. The deeper of the two likely has a robust crust above it below treeline. The depth of the snowpack varies greatly throughout the region and weak basal facets are present at the base of the snowpack.
Weather Summary
Thursday Night
Mainly cloudy. Variable northwest alpine wind 5-25 km/h. Treeline temperature dropping below -35°C.
Friday
Sunny. North alpine wind 10-20 km/h. Treeline temperature -35°C.
Saturday
Sunny. Variable alpine wind 5-10 km/h. Treeline temperature -30°C to -35°C.
Sunday
Increasing clouds. Northwest alpine wind 20-30 km/h. Treeline temperature -30°C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
Problems
Wind Slabs
Watch for signs of slab formation in the new snow, particularly in wind-affected areas and where buried surface hoar could be preserved (think sheltered openings at mid elevations).
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Storm Slabs
Recent storm snow covers a crust and isolated surface hoar. Investigate this interface, as the fresh snow settles and gains cohesion a reactive upper snowpack may develop.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Basal facets remain a real concern in steep, rocky terrain and other alpine features with thin-to-thick snowpack transitions. Recent avalanche activity tells us this problem is still lurking out there.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Jan 12th, 2024 4:00PM
