Avalanche Forecast
Issued: Apr 21st, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
jsmith,
Avalanche Canada
Avoid steep, rocky, and wind affected areas where triggering slabs are more likely.
Recent wind has varied in direction so watch for wind slabs on all aspects.
Summary
Confidence
Low
Avalanche Summary
A naturally triggered size 2 wind slab was reported on a northeasterly aspect in the alpine on Thursday. See MIN.
Observations are limited at this time of year, please consider sharing any information or photos you have on the Mountain Information Network to help guide our forecasts.
Snowpack Summary
Recent wind has varied in direction so watch for wind slabs on all aspects.
A crust exists up to ridgetop on south-facing slopes and on all aspects up to approximately 1500 m.
A weak layer buried in late March is down 30-50 cm and exists as surface hoar or small facets on north facing slopes and a crust with small facets on top on sunny aspects. Test results show that this layer may be reactive to human triggers in isolated locations in the alpine where the layer is well-preserved. See MIN.
The middle of the snowpack is strong and contains numerous hard crusts. Near the ground, weak faceted crystals exist. There hasn't been avalanche activity on this layer recently, but it remains on our radar and may become active when we experience change, such as rapid loading (heavy snowfall or rain) or prolonged warming.
Weather Summary
Friday Night
Cloudy with isolated flurries; 0-5 cm / 20 km/h south ridgetop wind / Temperature at treeline around -4 C / Freezing level 900 m
Saturday
Cloudy with flurries; 3-10 cm / 30 km/h south ridgetop wind / Temperature at treeline around -3 C / Freezing level 1400 m
Sunday
Cloudy with isolated flurries; 0-5 cm / 20 km/h south ridgetop wind / Temperature at treeline around -2 C / Freezing level 1500 m
Monday
Mostly cloudy with flurries; 5-10 cm / 30 km/h southwest ridgetop wind / Temperature at treeline around -4 C / Freezing level 1300 m
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Avoid steep, rocky, and wind effected areas where triggering slabs is more likely.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Problems
Persistent Slabs
30-50 cm of snow sits above a layer of facets and surface hoar on shaded slopes. On other slopes, this layer is a crust with facets above. Whumfing and settlements in the upper snowpack have been reported on this interface as well as snowpack test results indicating that human-triggering this slab is possible. Avoid steep open slopes capable of producing large avalanches.
Aspects: All aspects.
Elevations: Alpine.
Likelihood
Expected Size
Wind Slabs
Recent wind has varied in direction so watch for wind slabs on all aspects.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Apr 22nd, 2023 4:00PM
