Avalanche Forecast
Regions: Bow Valley, Highwood Pass, Kananaskis, North 40, Spray - KLakes.
We will remain at an elevated danger rating for the foreseeable future. The upper snowpack continues to settle and strengthen, but this sits upon problematic weak layers that are not to be trusted.
Confidence
High
Avalanche Summary
2 loose dry avalanches in the Chester area that are East facing appeared to be about 1 day old.
The North bowl between Mt. Chester and little Chester went size 2.5 as a slab in the last 2-3 days.
In Canmore on Monday, the first bowl on EEOR naturally avalanche to size 3 on a NE aspect in the alpine. This propagated across the whole bowl and ran well in to the gully out of view. Suspect the trigger was wind loading at ridge height.
Sometime Monday, Mt Buller avalanche paths also had a large Size 3 natural that propagated across the whole feature. Suspect cornice trigger, but unconfirmed.
Snowpack Summary
There is a lot going on in the snowpack but in a lot of ways it is simple. The top half of the snowpack is a 40-80cm dense slab that sits on top of 40-80cm of depth hoar and facets. This interface between the two is the January 30th interface and has produced repeatable sudden collapse test results. This is what is causing all of the bigger avalanches that have been reported. Unfortunately we will be in this pattern for the foreseeable future.
More Detail: Wind slabs exist in the alpine and if triggered, could easily step down to the January 30 layer(facets). The March 3 layer is mostly a sun crust on solar aspects and can be found down about 50cm. Conservative terrain choices that avoid being attached to a bigger piece of terrain is the way to go right now. Forecasters are sticking to low angle, well supported terrain only.
Weather Summary
Wednesday: A mix of sun and cloud with isolated flurries. Alpine temperatures of -6
45km/h West wind
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Fresh snow rests on a problematic persistent slab, don't let good riding lure you into complacency.
- Avoid exposure to overhead avalanche terrain; avalanches may run surprisingly far.
- Remote triggering is a big concern, be aware of the potential for wide propagations and large, destructive avalanches at all elevations.
Avalanche Problems
Wind Slabs
If triggered, these are likely to step down to the persistent slab and then to the basal facets. May find isolated windslabs in open treeline features.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Likely - Very Likely
Expected Size: 1.5 - 3
Persistent Slabs
This sits upon weak faceted crystals, sun crust or a dense layer that are perfect for slab avalanches. This layer is not reacting well to new loading, or even re-loading from wind.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Likely - Very Likely
Expected Size: 1.5 - 3.5