Watch for pockets of fresh wind slab at ridgetop. A buried weak layer looms in the west and central parts of the region. Check out our latest blog for advice on managing persistent avalanche problems.
Fresh wind slabs are likely to form at ridgetop elevations as upper level northwest winds pick up on Friday. Older wind slabs may remain triggerable by riders particularly where they sit over surface hoar.
A buried weak layer of surface hoar and facets exists 40-70 cm deep and is showing reactivity in snowpack tests. Avalanches on this layer are possible where overlying snow has formed a cohesive slab due to wind or settlement. This layer has not shown to be problematic in the Crowsnest area in the east of the region.
In the good visibility on Thursday, our field team observed three large natural size 1.5-2 persistent slab avalanches in big alpine terrain features near Elkford. We suspect they are of similar age as another avalanche reported in the same area on Tuesday. All are suspected to have run on the buried weak layer from November. This weak layer continues to show easy propagation in snowpack tests. In neighboring regions where it is buried deeper, this layer has produced several alarming rider-triggered avalanches.
Otherwise, avalanche activity in the region has been limited to explosive triggered wind slabs size 1-2 in the east of the region.
A thin surface crust may be found on steep south aspects. As ridgetop winds start to pick up from the northwest on Friday, 5-10 cm of recent snow is likely being reverse-loaded into atypical terrain features. Older wind slabs on more typical aspects, or soft snow in sheltered areas may sit over a layer of buried surface hoar in the east of the region.
A weak layer consisting of facets and surface hoar formed in November is now buried 45-65 cm deep in the west and central parts of the region. In the east, it may exist as a crust on solar aspects. This layer has produced large avalanches in recent days and continues to show reactivity in snowpack tests.
The lower snowpack consists of sugary and faceted snow, with a thick rain crust near the ground.
Total snowpack depths at treeline elevations are 75 to 155 cm.
Thursday night
Clear. Light northerly wind. Alpine low -15 C.
Friday
Mostly sunny. Ridgetop wind increasing to moderate-strong northwest. Alpine high -10 C.
Saturday
5-10 cm new snow. Light to moderate southwest ridgetop wind. Alpine high -15 C.
Sunday
Flurries. Light wind. Alpine high -22 C.
More details can be found in the Mountain Weather Forecast.
