Avalanche Forecast
Issued: Feb 9th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Deep Persistent Slabs and Wind Slabs.
mbender,
Avalanche Canada
Persistent slab avalanches continue to be reported in this region. The message remains the same – a complex, and generally weak snowpack is best managed by continuing to stick to lower angled, low consequence terrain.
Summary
Confidence
Avalanche Summary
On Wednesday there were two reports of natural deep persistent slab or persistent slab avalanches to size 3. These were viewed in the central part of the region and in the Dogtooth range. It seems both were triggered by heavy loads (cornice fall and wind slab avalanche stepping down) on north east and east aspects at 2500m.
There were also reports of wind slab avalanches to size 1.5 and 2.5 on north and east aspects in the alpine.
The possibility remains of triggering facets near the base of the snowpack, particularly on shallow, rocky slopes.
Snowpack Summary
20-50 cm of snow since late January is settling, or has been redistributed by moderate southwest wind. This overlies another layer of windslab, or surface hoar sitting on facets or a thin sun crust.
50-70 cm below the surface, the mid-pack contains a layer buried in early to mid January that remains a concern. It mostly exists as surface hoar, but facets or a crust may also be present.
A layer from late November is found 75 to 150 cm deep and is part of a generally weak, faceted snowpack.
Snowpack depths range between 80 and 180 cm at treeline, with the shallowest depths found on the eastern edge of the region.
Weather Summary
Thursday Night
Mainly cloudy with isolated flurries, accumulation 1-3cm. Moderate southwest ridgetop wind. Treeline temperature around -7 °C.
Friday
Mainly cloudy with scattered flurries, accumulation 3-5cm. Moderate to strong southwest ridgetop wind. Treeline temperature around -4 ºC. Freezing level rising to 1300m.
Saturday
Mainly cloudy with isolated flurries. Light to moderate west ridgetop wind. Treeline temperature around -5 ºC. Freezing level rising to 1200m.
Sunday
Mostly cloudy. Light to moderate west and southwest ridgetop wind. Treeline temperature around -6 °C. Freezing level around 1100m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- Approach lee and cross-loaded slopes with caution.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Uncertainty is best managed through conservative terrain choices at this time.
Problems
Persistent Slabs
Several weak layers in the upper and middle portions of the snowpack are at prime depths for human triggering. Stay disciplined and choose low consequence lines. Use extra caution in steep, wind-sheltered terrain where buried surface hoar is most likely to be preserved.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
It remans possible that riders could trigger a weak layer of facets near the base of the snowpack. The most likely area to trigger it is in shallow areas with variable snow depths. Avoid thin and rocky start zones and select routes that avoid traveling through or under large avalanche paths.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Recent new snow combined with wind has formed fresh wind slabs in lee terrain features.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 10th, 2023 4:00PM
