Avalanche Forecast
Regions: Bow Valley, Highwood Pass, Kananaskis, North 40, Spray - KLakes.
Warm temps continue to settle the upper snowpack into a slab at tree line and above and have become sensitive to triggering in the alpine. Backcountry users need to adopt a conservative mindset and make cautious terrain decisions for the foreseeable future.
Confidence
Moderate
Avalanche Summary
One Min report from Tuesday at Burstall Pass talks about remote triggering a size 1 from 30m away.
Snowpack Summary
Up to 5cm of recent snow overlies the December 26 rain crust that can be found to at least 2200m. The upper snowpack has gained some density with the warm temps. Wind slabs are present in Alpine and exposed treeline terrain, particularly just below ridgelines and in gully features. Some of these wind slabs have been reactive to remote triggering in the alpine. Below this new snow and wind slabs, the snowpack is very weak. Forecasters are tracking the Dec 16th surface hoar/facet layer down 10 to 20cm and the mid-November facet/surface hoar/depth hoar layer down 50 to 80cm. If avalanches are initiated on these layers they will likely step to ground through the very weak basal facets/depth hoar. It's not a pretty picture!
Weather Summary
Thursday will bring a mix of sun and cloud with moderate SW winds. Temperatures in the alpine will be between -6c and -11c.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Be aware of the potential for surprisingly large avalanches due to deeply buried weak layers.
- Be especially cautious as you transition into wind affected terrain.
Avalanche Problems
Wind Slabs
If triggered the wind slab is very likely to steep down to the deeper instability.
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood: Likely - Very Likely
Expected Size: 1 - 2
Deep Persistent Slabs
This layer should be monitored as elevation is gained. Despite being labelled as deep, it can be a ways off the ground. Entrainment is a major concern. These avalanches could run to valley bottom.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely - Very Likely
Expected Size: 1.5 - 2.5