Avalanche Forecast
Issued: Dec 16th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
JH,
Avalanche Canada
Triggering the Dec 1st surface hoar is still possible in areas that have not previously avalanched. With new snow hiding old avalanche debris, this is getting more difficult to assess. The safest way to manage this problem is by sticking to conservative terrain.
Summary
Confidence
Moderate
Avalanche Summary
On Saturday, we saw a few large storm slab avalanches in the steep terrain of the Eastern Highway Corridor.
On Thursday, just to our East an experienced group triggered a size 2 avalanche on the Dec 1 surface hoar and 1 skier was partially buried.
Earlier in the week, two separate groups reported near misses, triggering large avalanches on the Dec 1st surface hoar layer. One was on Ursus Minor, and the other was near the base of the 7 steps, in the Asulkan valley.
Snowpack Summary
Up to 20cm of recent snow buries wind effect, spotty surface hoar, and a thin sun crust in steep terrain.
A rain crust down 40-50cm is present up to 2100m.
A weak layer (Dec 1st surface hoar) is buried 50-90cm deep, continues to produce 'sudden' results in snowpack tests and has been the failure plane for several human triggered avalanches recently.
The base of our unseasonably thin snowpack is unsupportive and facetted in shallow areas at upper elevations.
Weather Summary
A ridge of high pressure moves into the interior. Expect stable weather, with warming temps and valley cloud, for the next couple of days.
Tonight: Clear periods, Alpine low -7°C, Moderate SW ridgetop winds.
Sun: Mainly cloudy, High -3°, Freezing level (Fzl) 1400m, Light SW Wind.
Mon: Sunny periods, Low -2 °C, High 0 °C, Fzl 2000m. Light S wind.
Tues: Flurries (5cm), Low -5 °C, High -2 °C, Light SW wind. Fzl 1600m.
Terrain and Travel Advice
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- Be mindful that deep instabilities are still present and have produced recent large avalanches.
Problems
Storm Slabs
Watch for fresh reactive slabs in wind-loaded features in the alpine and at treeline.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A weak layer of surface hoar is down 50-90 cm. This is a prime depth for rider triggering. To manage this problem, stick to conservative terrain. Below 2100m this layer may be bridged by a buried rain crust.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 17th, 2023 4:00PM
