Avalanche Forecast
Issued: Feb 11th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
shorton,
Avalanche Canada
Cold weather and lingering uncertainty about triggering large avalanches warrants careful travel in avalanche terrain. Read about managing these conditions in this forecaster blog.
Summary
Confidence
Weather Forecast
Brrrrrr! Cold and dry conditions persist under arctic air...
THURSDAY NIGHT: Clear skies, moderate to strong northeast wind, treeline temperatures drop to -30 C.
FRIDAY: Sunny, light east wind, treeline temperatures around -20 C.
SATURDAY: Sunny with a few clouds, moderate east wind, treeline temperatures around -15 C.
SUNDAY: Mix of sun and cloud, moderate south wind, treeline temperatures around -12 C.
Avalanche Summary
No significant avalanche activity has been reported since last weekend, but there have also been few observers due to the cold weather.
Over the weekend there was a very large (size 3) natural wind slab avalanche on a northeast aspect near Valemount, as well as a few size 2 avalanches in the Barkerville area. These included a mix of wind slab and persistent slab avalanches on a 40 cm deep surface hoar layer, mostly on treeline features (see some photos in the MIN reports here, here, and here). One was thought to have been initiated by a machine-triggered cornice fall. In the first week of February there was a flurry of persistent slab avalanche activity on the same surface hoar layer in the riding areas around Valemount and Blue River. Although the likelihood of triggering persistent slab avalanches is decreasing, this weak layer warrants assessment in open, sheltered slopes at treeline where this layer is likely pronounced and preserved.
Snowpack Summary
The upper snowpack is becoming soft and faceted with the cold temperatures, while wind may be forming slabs in lee features. 40-70 cm of snow from February is settling over a reactive weak layer of surface hoar. Reactivity on this layer has primarily been observed at treeline and in "treeline-like" features that are below treeline, although there could potentially be weak snow above crusts on south-facing alpine slopes. Additional weak layers may present in the lower snowpack, but are not a concern in most areas until we see significant snow loading or rapid warming.
Terrain and Travel
- Be careful as you transition into wind affected terrain.
- Carefully evaluate bigger terrain features on an individual basis before committing to them.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
Problems
Persistent Slabs
A weak layer of surface hoar is buried 40-70 cm deep that may be possible to human trigger. This layer has been most sensitive around treeline, but may also extend into alpine terrain and/or down into the trees.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Intermittent wind over the past few days could form triggerable wind slabs on lee features at upper elevations.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 12th, 2021 4:00PM
