Issued: Apr 20th, 2023 4:00PM
The alpine rating is Cornices, Deep Persistent Slabs and Persistent Slabs., the treeline rating is , and the below treeline rating is Known problems include
Isolated large to very large avalanches are still possible in moderate avalanche danger. Recent large cornice triggered deep persistent slabs are a good reminder to keep your head on a swivel when stepping out into a more complex terrain.
On Friday , 2 natural large deep persistent slab avalanches were observed by the Icefields road patrol, both on east aspect in the alpine triggered by a cornice failure.
Maligne road patrol saw no new natural avalanche activity on Friday.
Don't forget to post avalanche observations to the MIN.
Around 15cm of new snow this week sits on crusts on solar aspects, a melt freeze crust below tree line and old wind slab in exposed alpine
Below tree line is in a daily melt-freeze cycle. At tree line the mid-pack consists of multiple layers of sun crusts or facets. Depth hoar and basal facets at the base.
Saturday: Cloudy with sunny periods. Precipitation: Nil. Alpine temperature: High -2 °C. Ridge wind light to 20 km/h. Freezing level: 2000 m.
Sunday: Cloudy with sunny periods and isolated flurries. Precipitation: Trace. Alpine temperature: Low -4 °C, High 1 °C. Mostly light ridge wind occasionally gusting to 25 km/h. Freezing level: 2400 m.
Terrain and Travel Advice
- Avoid thin areas like rock outcroppings where you're most likely to trigger avalanches failing on deep weak layers.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
- Cornices become weak with daytime heating.
With increasing daytime temperatures and sun effect mature cornices have a potential to trigger the lingering deep persistent slab below.
Aspects: North, North East, East, South East, North West.
Deep Persistent Slabs
Several persistent weak layers in the midpack can be found as facets on polar aspects and sun crusts on solar aspects.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Valid until: Apr 21st, 2023 4:00PM