Avalanche Forecast
Regions: South Rockies.
Although a cooling trend means the snowpack is gaining strength, wind slabs remain a concern for riders. Watch for areas of reactive wind slabs on alpine lee features.
Confidence
Moderate - Recent weather patterns have resulted in a high degree of snowpack variability within the region.
Weather Forecast
FRIDAY NIGHT: Partly cloudy, strong southwest wind, treeline and alpine temperatures around -5 C, freezing level around 1200 m.
SATURDAY: A mix of sun and clouds with possible flurries, strong southwesterly wind, treeline high around -3 C, freezing level around 1500 m.
SUNDAY: Mainly sunny, light southwesterly wind increasing to strong, treeline high around -6 C, freezing level at valley bottom rising to 1500 by midday.
MONDAY: Cloudy with sunny periods, treeline high around -3 C, strong southwesterly wind, freezing level around 1500 m.
Avalanche Summary
On Thursday, three very large avalanches were reported from this region. These avalanches failed on the early December crust and showed wide propagation. They occurred on southwest to southeast aspects and were naturally triggered in response to rising temperatures and solar radiation.
On Wednesday, one very large (size 3) and several smaller (size 1-2) wind slab avalanches were reported on mostly north to east aspects in the alpine. A large cornice fall (size 3) was also reported.
The broader area including the South Rockies and neighbouring regions has been experiencing a sporadic pattern of very large avalanches over the last couple of weeks.
Snowpack Summary
Refreeze has created a melt-freeze crust up to 2000 m capping the recent snow which is settling fast and becoming dense due to warm temperatures. This snow sits on a variety of old surfaces, including soft snow in sheltered areas and wind slabs in exposed and open areas which formed over the past few days. Dry snow can still be found in the alpine but will likely be found as widespread wind slabs.
The most notable layer of concern in the snowpack is a crust that was formed in early December and is now typically down 80-150 cm. In the neighbouring Lizard-Flathead region, three very large avalanches were reported on this layer on Jan 13. This layer has created a tricky low likelihood, high consequence scenario which is best managed through conservative terrain choices and disciplined backcountry travel techniques.
Terrain and Travel
- Avoid freshly wind loaded terrain features.
- Be alert to conditions that change with elevation and wind exposure.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
Avalanche Problems
Wind Slabs
Wind slabs are likely confined to shady alpine areas where dry snow still exists. While these slabs may be thin, they could be poorly bonded to the underlying snow, so be extra cautious in lee terrain and convex rolls.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 2
Persistent Slabs
A persistent slab problem formed by a crust down 80-150 cm has created a low likelihood, high consequence scenario that is difficult to forecast. There has been an increase of avalanche reports on this layer since the past weekend. Although there was evidence of recent large avalanches on the layer, it is uncertain how the warm temperatures have affected the snowpack. Avoid likely trigger spots such as steep, rocky slopes with a shallow or thin to thick snowpack. Large additional loads like small avalanches or cornice falls can trigger deeper weak layers. The same feature or path can slide repeatedly when the persistent weak layer is reloaded with new snow.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 2 - 3.5