Avalanche Forecast
Issued: Jan 25th, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Deep Persistent Slabs and Wind Slabs.
stephen holeczi,
Parks Canada
Forecasters have low confidence in the snowpack. There is lots of good skiing and climbing but picking low consequence terrain is the only way to manage the deeper layers as they are hard to predict. Large (size 3) avalanches are still possible.
Summary
Weather Forecast
A mix of sun and cloud with some light afternoon flurries developing on Sunday. Freezing levels will be 1400m in the PM and alpine temperatures around -7. There could be a slight temperature inversion with cooler temperatures down low than up high. Alpine winds will be in the moderate range from the SW with strong gusts in some areas.
Snowpack Summary
Recent wind slabs can be found near ridge-tops. There is 40-60 cm above the Dec 31 layer of facets, surface hoar and sun crust which is slowly becoming less reactive. The bottom layer of the snow-pack consists of weak facets and depth hoar, except for deeper snow-pack areas (over 2m) which have basal facets but not as prevalent.
Avalanche Summary
A large natural avalanche over Cascade waterfall occurred yesterday which went on the basal facets/depth hoar, possibly triggered by warm temperatures and solar input. One other size 2.5 cornice triggered wind slab stepping down to the persistent layer was observed in the last 24 hours. This was a SE aspect in the Sunshine backcountry.
Confidence
Problems
Persistent Slabs
The late Dec layer of surface hoar, facets or sun crust is buried 40-60cm throughout the region and producing variable results depending on location and what crystal form is present. There is still high uncertainty as to how reactive this layer is.
- If triggered the persistent slab may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
In the past week we have seen several avalanches initiate or step down to this deep persistent layer of facets, depth hoar and crusts. Conservative terrain choices are your best defence as this problem is almost impossible to forecast.
- Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.
- Avoid shallow snowpack areas where triggering is more likely.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Wind slabs exist near ridge-tops. With increased winds on Sunday these will remain possible to trigger.
- Use caution in lee areas. Recent wind loading has created wind slabs.
Aspects: North, North East, East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Jan 26th, 2020 4:00PM
