Avalanche Forecast
Issued: Mar 17th, 2023 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
jsmith,
Avalanche Canada
Recently formed storm slabs may remain reactive to human triggers; especially on sunny aspects where they are sitting on a crust.
Minimize exposure to steep, sun-exposed slopes when the solar radiation is strong.
Summary
Confidence
Avalanche Summary
Numerous rider triggered size 1 storm slabs were reported on a variety of aspects at treeline and above on Thursday. The majority of the avalanches occurred on sunny aspects in the alpine where the recent snow was sitting on a crust.
Additionally, a naturally triggered size 2 storm slab was reported on a sunny aspect in the alpine near Blue River.
Snowpack Summary
Moderate southwesterly wind and 20-30 cm of recent snow have created wind slabs that may remain reactive to human triggers.
The sun and warm temperatures are beginning to make their mark on the snowpack. On solar aspects and at lower elevations the top layer of snow may become moist in the afternoons and frozen in the mornings.
Below the new snow are a variety of surfaces. These include surface hoar, 3 to 10 mm, on shady slopes at all elevations, wind-affected surfaces at treeline and above, and sun crust on sunny aspects.
The mid-snowpack is generally strong but the lower snowpack is a different story.
The November facets are still prominent at the base of the snowpack. They are showing signs of improving but this layer remains a significant concern in rocky, shallow, or thin to thick snowpack areas at treeline and above.
Weather Summary
Friday Night
Partly cloudy / 20 km/h south ridgetop wind / Temperature at treeline around -10 C / Freezing level valley bottom
Saturday
Mix of sun and cloud / 10 km/h south ridgetop wind / Temperature at treeline around -4 C / Freezing level 1600 m
Sunday
Sunny / 10 km/h southeast ridgetop wind / Temperature at treeline around -3 C / Freezing level 1700 m
Monday
Mostly cloudy / 30 km/h southeast ridgetop wind / Temperature at treeline around -3 C / Freezing level 1700 m
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Minimize exposure to sun-exposed slopes when the solar radiation is strong.
- Avoid exposure to overhead hazards when solar radiation is strong.
- Avoid exposure to slopes that have cornices overhead.
- Closely monitor how the new snow is bonding to the crust.
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
Problems
Storm Slabs
Recently formed storm slabs may remain reactive to human triggers; especially on sunny aspects where they are sitting on a crust.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
A weak layer of facets exists near the base of the snowpack. The likelihood of human triggering is low given the layer's depth, but large triggers such as cornice failures or smaller avalanches in motion have the potential to produce very large avalanches with surprisingly wide propagation. Suspect terrain for human triggering includes steep, shallow, and rocky terrain where the snowpack transitions from thin to thick.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 18th, 2023 4:00PM
