Avalanche Forecast
Regions: Kootenay Boundary.
Strong wind and some new snow may form wind slabs. Don't be complacent about the buried weak layer that continues to surprise riders.
Confidence
High -
Weather Forecast
THURSDAY NIGHT: Clear skies, moderate to strong southwest wind, alpine temperature -1 C, freezing level 1700 m.
FRIDAY: Cloudy with snowfall, accumulation 5 to 10 cm, moderate southwest wind, alpine temperature -4 C, freezing level 1400 m.
SATURDAY: Cloudy with snowfall, accumulation 10 cm, light south wind, alpine temperature -5 C, freezing level 1300 m.
SUNDAY: Mix of sun and cloud with isolated flurries, light west wind, alpine temperature -9 C, freezing level 1000 m.
Avalanche Summary
A handful more avalanches were triggered by riders on the February 22 surface hoar layer described in the Snowpack Summary. The avalanches were on west, north and east aspects, they were 20 to 40 cm deep, and they occurred around 1900 to 2300 m. The avalanches were small (size 1 to 1.5) to large (size 2).Â
Similar avalanches have been observed in the region for the past week, being generally small to large (size 1 to 2) and between 1800 and 2300 m on northwest to east aspects. This trend is suspected to continue as this layer slowly gains strength.
Snowpack Summary
Strong southwest wind and around 5 to 10 cm of snow may form new wind slabs in lee terrain features on Friday. The most suspect areas will be immediately adjacent to ridgelines.
Around 30 to 50 cm of snow overlies a touchy layer of feathery surface hoar crystals. The layer is most commonly found in open trees (e.g. in this MIN) or sheltered terrain around upper below treeline, treeline, and lower alpine elevations. Check out the latest forecaster blog that offers a deeper dive into these conditions.
The remainder of the snowpack is strong and well-settled.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Avalanche Problems
Persistent Slabs
Around 30 to 50 cm of snow overlies a weak layer of surface hoar. The layer has been most problematic on northwest to northeast aspects between 1600 m and 2300 m, but the layer may exist on all aspects and at all elevations. Riders will be capable of triggering this layer for some time until there is a substantial change in the snowpack and/or weather. Assess the layer prior to committing to avalanche terrain or adopt a conservative mindset to avoid the problem.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Possible
Expected Size: 1 - 2
Wind Slabs
New wind slabs may form on Friday with strong southwest wind and 5 to 10 cm of new snow. The most suspect terrain will be leeward slopes immediately adjacent to ridge lines. Wind slabs could step down to the buried surface hoar layer, forming large avalanches.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 1 - 2