Avalanche Forecast
Issued: Dec 6th, 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.
shorton,
Avalanche Canada
Avalanche danger will gradually increase in wind-affected terrain this week. There have been some reports of a localized dangerous weak layer in the Barkerville area.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations.
Weather Forecast
MONDAY NIGHT: Clear skies, no precipitation, light wind from the west, treeline temperatures around -15 C.
TUESDAY: Increasing cloud with some light flurries in the afternoon, no significant precipitation, moderate wind from the southwest, treeline temperatures warming to -10 C.
WEDNESDAY: 5-15 cm of low density snow by the morning with some clearing skies in the afternoon, moderate wind from the west, treeline temperatures around -12 C.
THURSDAY: Partly cloudy skies, no precipitation, light wind from the west with some gusts to 40 km/h, treeline temperatures around -12 C.
Avalanche Summary
In most parts of the region there were no reports of avalanches over the weekend, however, one size 2 avalanche was triggered in a north-facing bowl in Barkerville. This avalanche is suspected to have occurred on a 50 cm deep surface hoar layer that our field team also observed in that area.
Otherwise, the only other recent reports are from Thursday Dec 2, when two very large (size 3) avalanches were reported in the Valemount - Blue River corridor. One failed naturally on a south aspect, and the other was triggered by a cornice collapsing on a north-facing slope. Both avalanches ran on the early season crust/facet layer that is 150-200 cm deep in this area.
Snowpack Summary
Pockets of wind slab are found in lee features at upper elevations, with fun powder in protected areas and depressions. Open areas and higher elevations are windswept and hold little fresh snow. The early December crust exists below 1800 m on all aspects and has 10-30 cm of low density snow above it.
The snowpack structure is generally strong and settled with an early season crust layer about 150-250 cm deep in the alpine. One potential exception is in the Barkerville area where there have been some reports suggesting a weak layer of surface hoar may be 50 cm below the surface. Extra caution should be taken in this area since little is known about this layer at this time.
Check out our latest Forecaster Blog here.
Terrain and Travel
- Be careful as you transition into wind affected terrain.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Back off if you encounter whumpfing, hollow sounds, or shooting cracks.
- Caution around convexities or sharp changes in terrain.
Problems
Wind Slabs
Wind speeds will increase as a weak frontal system crosses the region on Tuesday. The wind will likely form some unstable slabs on the downwind side of ridges.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
We are suspicious about a buried surface hoar layer in the Barkerville area. Reports are limited, but there has been at least one human triggered avalanche and this MIN report from our NoRo field team identifying the weak layer 50 cm below the surface. There is no evidence of this weak layer in other parts of the region.
If travelling around Barkerville we suggest conservative terrain selection and gathering more information, as this type of weakness can surprise riders at lower elevations in open trees.
Aspects: North, North East, East, North West.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Dec 7th, 2021 4:00PM
