Avalanche Forecast
Regions: Banff, Banff Yoho Kootenay, East Side 93N, Field, Kootenay, LLSA, Lake Louise, Little Yoho, Sunshine, West Side 93N.
A major avalanche cycle is underway and will last through to Monday. Avalanches will run to the valley bottom. Pay attention to avalanche warning signs at popular locations in the Emerald Lake and Lake Louise area and Sulphur mountain trail. Avoid all avalanche terrain and pass this message along to your hiking friends.
Confidence
High
Avalanche Summary
No significant avalanches were reported on Friday at 3:30 pm, but expect avalanches are occurring with treeline highs at +16C and still rising with intense solar input. The snow surface was frozen on Friday morning and was isothermal by 1:00 pm in thinner areas. Some size 1-2 wet loose avalanches were observed, one scrubbed to the ground, but the day's heat is now upon us until later this evening.
Snowpack Summary
The heat is on! Sky-high freezing levels will destabilize the snowpack early in the day, with no overnight refreezing expected for Friday through Monday. Expect wet, sloppy snow on all aspects and elevations and unsupportive isothermal snow (slush) at the treeline and below. We expect many large avalanches to fail on the ground.
Weather Summary
Friday night, valley bottoms may cool to near freezing, but treeline and above will not freeze, and temperatures may be up to +5C overnight. The avalanche hazard will increase early Saturday morning with freezing levels climbing to 3500 m, temperatures near 20C, strong solar input, and light wind. The same is expected for Sunday.
Terrain and Travel Advice
- Avoid all avalanche terrain during periods of intense solar radiation.
- Avoid exposure to overhead avalanche terrain as temperatures increase.
Avalanche Problems
Deep Persistent Slabs
This dangerous problem results from a weak snowpack base formed in early winter, now with the entire winter's snowpack above it. This problem has been difficult to predict, except this weekend when we're almost certain to see many large avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Certain
Expected Size: 2 - 3.5
Cornices
Cornices will fall off this weekend for sure. With the high freezing levels and direct sun exposure, the mountains will begin to shed. Do not exposure yourself below or close to any corniced features.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Certain
Expected Size: 1.5 - 2.5
Loose Wet
We expect wet snow avalanches on all aspects and elevations, especially when the sun cooks the slopes. Slush and wet snow will run like water down gullies and through rock bands: the spring melt is on.
Aspects: All aspects.
Elevations: All elevations.
Likelihood: Certain
Expected Size: 1 - 2.5