Avalanche Forecast
Issued: Jan 29th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Deep Persistent Slabs, Wind Slabs and Persistent Slabs.
lbaker,
Avalanche Canada
We continue to receive reports of very large deep persistent slab avalanches in the region. Small avalanches, even wind slabs, have the potential to trigger larger avalanches deeper in the snowpack. Continue to choose low-consequence terrain and avoid terrain features capable of producing large avalanches.
Find the newest blog here to learn more about managing this weak snowpack in the backcountry.
Summary
Confidence
Moderate
Avalanche Summary
On Saturday, a natural size 4 deep persistent slab avalanche was reported. The avalanche started as a wind slab in steep rocky terrain and stepped down to the ground. This avalanche was 80 to 200 cm deep and ran full path.
A skier remote size 1.5 wind slab avalanche was reported to have run on surface hoar below a wind slab. Numerous natural loose dry and wind slab avalanches were reported on all aspects of the alpine.
Early last week a size 3 skier triggered a deep persistent avalanche and a natural size 3.5 deep persistent avalanche was reported in the Dogtooth range. Check out the MIN reports for details.
Snowpack Summary
5-15 cm of new snow is being redistributed into soft slabs in exposed areas. New snow overlies a variety of surfaces including previously wind affected surfaces, a small layer of surface hoar and a sun crust.
The mid-snowpack contains a couple of weak layers. The first is down 30 to 50 cm and is a layer of surface hoar from early January. The second is a layer of surface hoar, facets, and crust created in December and found 40 to 60 cm down. The surface hoar is most prevalent in sheltered areas while crusts with faceted snow are more widespread.
The bottom of the snowpack is weak, faceted and contains a weak layer from late November. Snowpack depths range between 80 and 180 cm at treeline and are shallowest in the eastern part of our region.
Weather Summary
Sunday Night
Clear with cloudy periods. Northerly ridgetop winds 20 km/h. Alpine low temperatures of -20°C.
Monday
Sunny with clouds increasing in the afternoon. Northerly ridgetop winds switch to westerly in the afternoon 20 km/h. Alpine high of -15°C.
Tuesday
A mix of sun and cloud with isolated flurries, trace accumulations. Westerley ridgetop winds 20 km/h. Alpine high of -12°C.
Wednesday
A mix of sun and cloud with isolated flurries, trace accumulations. Southwesterly ridgetop winds 20 km/h. Alpine high of -10°C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for wind-loaded pockets especially around ridgecrest and in extreme terrain.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- Uncertainty is best managed through conservative terrain choices at this time.
Problems
Deep Persistent Slabs
A weak layer near the base of the snowpack, buried in November, has been recently reactive in the Dogtooth Range and Western Purcells. Human and natural triggering of this layer remains possible, especially in shallow areas with variable snow depths. Avoid thin and rocky start zones and choose well supported terrain features. And check out the latest blog for information on how to manage this problem.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Pockets of stubborn wind slabs are found at higher elevations. Recent winds have varied from east to west throughout the region - look for wind affected snow on all aspects as you approach or descend from ridgelines.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Several weak layers sit in the upper and mid snowpack at prime depth for human triggering. Avoid convex rolls in sheltered terrain where buried surface hoar may be present. Choose supported terrain features, and avoid large open slopes.
Smaller avalanches could create a "domino effect" and create large avalanches with wide propagation.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 30th, 2023 4:00PM
