Avalanche Forecast
Issued: Jan 22nd, 2020 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs, Persistent Slabs and Deep Persistent Slabs.
william lawson,
Parks Canada
Our confidence in the snowpack is low. The considerable rating is not intended to be the green light for committing terrain. Natural avalanches activity has subsided though human triggered AVALANCHES are still POSSIBLE.
Summary
Weather Forecast
Unsettled weather is expected for the reminder of the week with a gradual warm up Friday. Freezing levels will remain at valley bottom into the weekend. Flurries through the weekend could amount to 10-15cm by Monday.
Snowpack Summary
Wind effect and isolated windslabs exist in lee areas in the alpine from recent loading. There is 40-60 cm above the Dec 31 layer of facets, surface hoar and sun crust which is slowly becoming less reactive. Concern remains for the weak layers of facets and depth hoar near the base of the snowpack.
Avalanche Summary
No new natural avalanches observed over the past few days. Explosive control Tuesday on highway 93 North produced varied results. Much of the control work produced smaller then expected results, though one large size 3.5 was triggered on the deep persistent problem. This variability builds little confidence in the snowpack.
Confidence
Problems
Wind Slabs
Wind slabs have been less reactive, even with explosive control. Isolated pockets of wind still exist in lee areas.
- If triggered the wind slabs may step down to deeper layers resulting in large avalanches.
- Use caution in lee areas. Recent wind loading has created wind slabs.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
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
We have seen a few recent avalanches on the deep persistent problem of basal facets and depth hoar, often beginning as wind slabs and then stepping down to the weak base. Conservative terrain choice is your best defence.
- Avoid shallow snowpack areas where triggering is more likely.
- Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 23rd, 2020 4:00PM
