Avalanche Forecast
Issued: Jan 26th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Storm Slabs.
rgoddard,
Avalanche Canada
Snowfall amounts will vary throughout the region. Storm snow will be covering a variety of near-surface weak layers and deeper buried weak layers.
Be mindful that even sluffing could have a "domino effect" and produce large avalanches.
Mellow terrain with fewer consequences will be the best option until things settle.
Summary
Confidence
Moderate
Avalanche Summary
Wednesday's avalanche activity was made up of wind slabs and persistent slabs that were triggered naturally and with the use of explosives.
Although persistent and deep persistent avalanches have been on the decline, the recent and upcoming change in weather may change this.
Snowpack Summary
New snow will be falling on a snowpack that within its top 50 cm contains several layers that could pose a threat with this new load.
Faceted snow, surface hoar (3 to 10 mm), and a crust are already buried 10 to 20 cm down. The surface hoar is found in sheltered areas up to 2200 m and the crust is present on steep solar aspects. At high elevations, new snow will be covering up older wind slabs.
A freezing rain or rime crust buried on January 18 now sits about 15 to 30 cm deep. More layers of concern (crusts, facets, and surface hoar) can be found in the upper snowpack between 30 to 50 cm down. They have yet to produce avalanche activity but they are something to keep an eye on.
Our main layers of concern include a surface hoar layer developed in early January, down roughly 50 to 70 cm, and a melt-freeze crust from late December that is now down approximately 70-90 cm. These layers are responsible for our persistent slab problem.
Our deep persistent slab problem stems from a weak layer created in mid-November and it is now buried 100 to 190 cm deep. These layers are a major concern and can produce large or even very large avalanches with human or machine triggers.
Weather Summary
Thursday Night
Cloudy, up to 14 cm accumulation focused mostly in the western area of our region, winds southwest 20 to 30 km/h, treeline temperatures -4 C and freezing levels up to 1500 m.
Friday
Mostly cloudy, up to 7 cm accumulation in the eastern of the region winds northwest 15 km/h gusting to 40, treeline temperatures around -5 C.
Saturday
Increasing sun, trace accumulation ending in the morning, winds northeast 15 to 30 km/h, treeline temperatures -15 C.
Sunday
Sunny with some cloud, no accumulation, winds north 10 to 20 km/h, treeline temperatures -18 C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Storm slabs in motion may step down to deeply buried weak layers resulting in very large avalanches.
- Carefully assess open slopes and convex rolls where buried surface hoar may be preserved.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
Problems
Persistent Slabs
A persistent weak layer of surface hoar is buried 50 to 70 cm down. This depth is prime for human triggering. Below treeline this layer may present as a rain crust.
Deeper in the snowpack, near the ground, the snowpack is very weak and can be triggered under the right circumstances. Be especially suspicious of shallow, rocky, or cross-loaded areas with variable snow depths.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Storm Slabs
New snow arriving Thursday night and into Friday will vary in accumulated amounts with much more falling in the west. This new snow will be covering a snowpack that within the first 30 to 50 cm, contains a several layers that could be reactive with this new load.
Moderate winds will be accompanying this new snow so expect fatter deposits in the lee of features.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 27th, 2023 4:00PM
