Avalanche Forecast
Issued: Jan 31st, 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.
llarson,
Avalanche Canada
Exercise patience and maintain conservative terrain choices. Small wind slab avalanches have the potential to trigger larger avalanches deeper in the snowpack.
Find the newest blog here to learn more about managing this weak snowpack in the backcountry.
Summary
Confidence
Moderate
Avalanche Summary
On Monday, explosives control produced a few size 1 wind slabs.
On Sunday, explosives control produced several slab avalanches on all aspects of the alpine with results up to size 2. It also triggered a size 3 deep persistent slab avalanche that pulled to the ground on a west aspect.
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.
Snowpack Summary
5 to 10 cm of accumulated new snow will further build wind slabs in exposed areas at the treeline and above. These new wind slabs have developed on 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
Tuesday Night
Mainly cloudy with isolated flurries, 3 to 5 cm. Winds 20 to 30 km/h west, Treeline temperatures -15 °C.
Wednesday
Mainly cloudy, with 5 to 10 cm of new snow. Winds 20 to 30 km/h, treeline temperatures of -12 °C.
ThursdayMainly cloudy, trace accumulations. 10 to 20 km/h southwest winds. Treeline temperatures -10 °C.
FridayIncreasing clouds, 2 to 5 cm of new snow, 10 to 20 km/h southwest winds, Treeline temperatures -9 °C.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Approach lee and cross-loaded slopes with caution.
- 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, continues to be reactive. Human and natural triggering of this layer remain possible, especially in shallow areas with variable snow depths. Avoid thin and rocky start zones and select routes that avoid exposure to large avalanche paths. Check out the latest blog for information on how to manage this problem.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Wind slabs are found at treeline and alpine elevations and may be forming in sheltered terrain where strong winds have been redistributing soft snow further downslope. Watch for reverse loading and cross-loading from recent variable winds.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
Several weak layers sit in the upper and mid snowpack at prime depths for human triggering. Avoid convex rolls in sheltered terrain where buried surface hoar may be present. Stay disciplined and choose well supported, low consequence lines.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 1st, 2023 4:00PM
