Issued: Apr 23rd, 2023 4:00PM
The alpine rating is Deep Persistent Slabs, Cornices and Loose Wet., the treeline rating is , and the below treeline rating is Known problems include
Sunday night is expected to have less of an overnight freeze than previous nights and Monday may start warm. The thick high clouds potentially will hold onto the warm air overnight. If Monday starts warm, this could increase the reactivity of cornices and deep persistent slabs.
There was an avalanche Fatality in Banff Park near Lake Louise Saturday from a deep large human triggered slide. On Friday, 2 natural large deep avalanches were observed, both on East aspect in the alpine triggered by a cornice failure.
Maligne road patrol saw no new natural avalanche activity on Friday.
Post avalanche observations to the MIN.
10cm of new snow from last week has settled onto sun crusts on solar aspects with a melt-freeze crust below tree line. Old wind slab is on exposed alpine terrain.
A weak layer of sun crust or facets lingers in the mid-pack but the main concern is the depth hoar and basal facets at the bottom of the snowpack causing our deep persistent slab problem.
Parkers ridge weather on Monday will bring sun and cloud, no new snow, high of 1 °C, light winds, and 2400m freezing level. Tuesday will have sun with flurries, -5 °C in the morning then a high of -2 °C, gusting 35 km/h winds, and 1900m freezing level. Wednesday will be sun and cloud, -7 to 0 °C, light winds, and 2200m freezing level.
Terrain and Travel Advice
- Cornices become weak with daytime heating.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
- Avoid exposure to slopes that have cornices overhead.
Deep Persistent Slabs
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.
There is expected to be less of a freeze Sunday night and Monday the freezing level will be 2300m or higher depending on weather variables.
Aspects: South East, South, South West, West.
Elevations: Treeline, Below Treeline.
Valid until: Apr 24th, 2023 4:00PM