Avalanche Forecast
Issued: Dec 29th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
mconlan,
Avalanche Canada
New wind slabs may be reactive to riders on Thursday.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
WEDNESDAY NIGHT: Cloudy with snowfall, accumulation 5 cm, 20 to 50 km/h southwest wind, alpine temperature -22 C.
THURSDAY: Mostly cloudy with isolated flurries and afternoon clearing, trace accumulation, 10 to 20 km/h north wind, alpine temperature -21 C.
FRIDAY: Clear skies with no precipitation, 10 to 20 km/h northeast wind, alpine temperature -22 C.
SATURDAY: Cloudy with snowfall, accumulation 5 cm, 60 to 90 km/h southwest wind, alpine temperature -16 C.
Avalanche Summary
A few small wind slab avalanches were observed in steep, alpine, lee terrain features.
The latest avalanche activity on the early-December weak layer described in the snowpack summary was from Monday. This included two natural avalanches and one triggered by a rider. They were large (size 2 to 3), observed on all aspects, and found between 1700 m and up to 2600 m.
Snowpack Summary
A bit of new snow and strong wind are likely to form new wind slabs in exposed terrain Wednesday night. These slabs will overly previously wind-affected snow, sugary faceted grains, or surface hoar.Â
A weak layer of feathery surface hoar may be found around 30 to 50 cm deep. It is most likely to be found in sheltered alpine features, around treeline, or open features below treeline. Although avalanche activity hasn't been prominent on this layer, it has been reactive in snowpack tests.
Sugary faceted grains may be found around the early-December melt-freeze crust 80 to 150 cm deep. The layer is most prevalent around 1700 m to 2200 m but could exist at lower and higher elevations for pockets of the region. This layer is spatially variable, with many areas showing good bonding to the crust whereas other areas showing concern. This layer has recently been most reactive where it remains shallower than about 100 cm. Learn more about how to manage this problem here.
Terrain and Travel
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Carefully evaluate steep lines for wind slabs.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
Problems
Wind Slabs
Strong wind and a bit of new snow on Wednesday night may form new wind slabs in exposed terrain features at higher elevations. Slabs that form could be touchy, as they may overly weak faceted snow or surface hoar that formed during the clear, cold spell.
Aspects: North, North East, East, South East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
We continue to receive sporadic reports of people triggering a weak layer of faceted grains around a melt-freeze crust that formed in early December. This layer is found around 80 to 150 cm deep and is most common at elevations between 1700 m and 2200 m.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Dec 30th, 2021 4:00PM
