Avalanche Forecast
Issued: Apr 4th, 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.
swerner,
Avalanche Canada
Storm slabs may continue to be reactive to rider triggering.Dynamic spring weather could bring you intense sun or snowfall, either of which would increase the avalanche danger. Observe your local conditions and let that inform your terrain choices.
Summary
Confidence
Moderate
Avalanche Summary
No new reports by 4 pm on Tuesday.
On Monday, natural solar-induced slab avalanches were reported up to size 2.5 and the recent storm snow continued to be reactive to rider triggering up to size 1.5. Reports indicate that the Selkirks seem to be the most reactive with rider remote-triggered slabs in the upper 50 cm of snow. These are failing on a surface hoar layer buried near the end of March or a crust on solar aspects. These avalanches were primarily on north and east aspects from 1700 m to 2200 m. This MIN Report from Sunday indicates what is mentioned above.
When the sun pokes out you may see natural wet or dry loose avalanches from solar aspects. Spring weather can change quickly so be willing and ready to adjust your trip to the conditions.
Snowpack Summary
At higher elevations, 15-40 cm of mostly soft storm snow is settling over a widespread, crust except for north-facing slopes at treeline and above, where it sits on old, faceted surfaces, and surface hoar in sheltered terrain. Reports indicate that the surface hoar layer (down 50 cm) was surprisingly reactive to human triggering in the Selkirks on Monday, especially on northeasterly slopes from 1700 m to 2100 m.
Isolated pockets of wind slab exist on leeward slopes and a thin surface crust may be seen on solar aspects to ridgetop.
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. This layer remains a concern in rocky, shallow, or thin to thick snowpack areas at treeline and above.
Weather Summary
Tuesday Night
Mix of clear and cloud. Possible trace of snow. Ridgetop wind 10-15 km/h freezing level falling to valley bottom. Treeline low around -7°C.
Wednesday
A mix of sun and cloud. Light variable wind from the southwest. Freezing level rising to 1500 m. Treeline high around -3°C.
Thursday
Mix of sun and cloud. Ridgetop wind 30-40 km/h from the southwest. Freezing level at valley bottom in the morning, rising to 1500 m.
Friday
Mostly cloudy. 3-5 cm of snow is expected. Southwest ridgetop wind 40 km/h. Freezing level at valley bottom in the morning, rising to between 1700 m.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Don't be too cavalier with decision making, storm slabs may remain sensitive to human triggering.
- Surface hoar distribution is highly variable. Avoid generalizing your observations.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Problems
Storm Slabs
Last weekend's storm brought 15-40 cm of snow across the region. The storm slab has been reactive to natural triggers like the sun on solar slopes and to rider triggers on northeasterly slopes where it sits above a buried surface hoar interface down 50 cm. In other places, the recent snow has already settled and bonded.
Moderate southwest wind may have formed deeper, more reactive deposits of snow on leeward slopes.
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.
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: Apr 5th, 2023 4:00PM
