Issued: Apr 24th, 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
The trend for the next few days is less overnight freeze and increasing freezing levels raising the potential of increased reactivity. Your strategy is to start and end early, avoid cornices, and anticipate natural activity to escalate with full depth releases possible.
Monday's Maligne and Icefield's patrols noted nothing new. There was an avalanche Fatality in Banff Park near Lake Louise Saturday from a deep large human triggered slide. Last week a few large cornice triggered avalanches were noted on Alpine East aspects.
Post avalanche observations to the MIN.
A dusting of snow overnight rests on sun crusts on solar aspects and a melt-freeze crust below tree line. Old wind slabs are on exposed alpine terrain. A layer of sun crust or facets linger in the mid-pack. The main concern is the depth hoar and basal facets at the bottom causing our deep persistent slab problem.
Parkers ridge weather on Monday night will be clear and -4 °C. Tuesday is sun, cloud, flurries, -2 °C, and 1900m freezing level. Wednesday's freezing level is forecast to increase to 2500m and Thursday's will be 3000m.
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
Cornices are large and ominous. The rising freezing levels will weaken them. When they fall, they can trigger large avalanches or just be a hazard by their sheer mass.
Aspects: All aspects.
This problem will be increasing in frequency the next few days as less overnight freeze occurs and rising daytime freezing levels.
Aspects: South East, South, South West, West.
Elevations: Treeline, Below Treeline.
Valid until: Apr 25th, 2023 4:00PM