Avalanche Forecast
Regions: South Rockies.
Strong wind forecast overnight will likely transport recent snow into fresh, reactive wind slabs at upper elevations. Watch for signs of instability like shooting cracks in wind loaded lee features such as beneath ridge crests and roll-overs.
Confidence
Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.
Weather Forecast
Tuesday night: Increasing cloud. Westerly wind increasing to strong above 2500 m. Alpine temperatures around -6. Freezing level 1000 m.
Wednesday: Up to 5 cm new snow. Strong westerly wind easing to light. Alpine high temperatures around -4. Freezing level 1700 m.
Thursday: Mix of sun and cloud. Light wind. Alpine high temperatures around -3. Freezing level 1700 m.
Friday: Mix of sun and cloud. Northwest wind increasing to moderate. Alpine high temperatures around -1. Freezing level 2000 m.
Avalanche Summary
On Monday, small natural wind slabs were starting to pop in steep, unsupported alpine features in the south of the region where recent snowfall amounts have been greatest. With strong overnight winds forecast, more wind slab activity is expected on Tuesday.
Snowpack Summary
20-30 cm of new snow has been accumulating incrementally over recent days on top of wind affected surfaces in the alpine and refrozen crust lower down after light rain recently wet the snow surface below about 1700 metres. This new snow is most likely being blown around by strong winds forecast overnight Tuesday and into Monday morning, forming fresh wind slabs in lee terrain features at upper elevations.
Around 30 to 60 cm of snow sits above a layer of sugary faceted grains that were buried in mid-February. In some areas, there may be an old layer of feathery surface hoar or facets from late January down 50 to 80 cm deep. There have been no reported avalanches on either of these layers in the region since March 9th in the Crowsnest.
The mid pack is firm and well settled. Some faceted snow and a decomposing melt-freeze crust can be found near the base of the snowpack.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
Avalanche Problems
Wind Slabs
Strong westerly wind forecast overnight will likely transport recent snow into fresh, reactive wind slabs at upper elevations. Watch for wind loaded pockets in lee terrain features such as beneath ridge crests and roll-overs.
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 1.5