Avalanche Forecast
Issued: Nov 25th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Loose Dry and Wind Slabs.
SH,
Avalanche Canada
A classic Rockies snowpack is starting to form with a weaker base and slabs on top. While winds remain elevated and new snow accumulates, ice climbers and gully skiers should consider the potential for heavy sluffing. We have significant uncertainty due to minimal field observations.
Summary
Confidence
Moderate
Avalanche Summary
Some smaller slabs were noted at the Lake Louise ski hill but limited visibility overall. A notable size 2 wind slab was remotely triggered 2 days ago on Observation Sub Peak. It had impressive propagation on the underlying weak facets and scrubbed to the ground. Not in Banff, but an ice climber close call on Thursday with loose dry avalanches on Shades of Beauty in Jasper is very relevant to our area.
Snowpack Summary
5-15cm over the last 24 hours (higher amounts West of the divide and in the North). Strong to extreme SW winds and warm temperatures over the past 36 hours have promoted wind slab growth at higher elevations (10-30cm thick have been observed). The snowpack below these slabs is a mix of facets, some spotty surface hoar, and sun crust on steep south aspects. There is even some classic Rockies depth hoar forming at the base in thinner areas. 40-80 cm of total snow exists at treeline throughout the region, with up to 120 cm in loaded alpine features.
Weather Summary
5-10cm overnight and moderate winds. A warm front on Saturday with flurries and 40-50kmh ridgetop SW winds, increasing to 60 kmh in the afternoon. Expect freezing levels to 1400m.
On Sunday, a cold front with 5-10cm in Lake Louise and Yoho areas, and lesser amounts (5cm) in the rest of the regions. Expect continued strong winds and valley bottom freezing levels.
For more information specific to the forecast region, see https://www.avalanche.ca/weather/forecast
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for areas of hard wind slab on alpine features.
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Loose avalanches may start small but they can grow and push you into dangerous terrain.
Problems
Persistent Slabs
There's a real classic mix of facets, some spotty surface hoar, sun crust on solar aspects, and even some depth hoar at the base of the snowpack. Anywhere a slab exists over this weaker base has the potential for avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Dry
While winds are elevated and there are new snow inputs, loose dry avalanches can be expected. This is mainly a problem for ice climbers and skiers in steep, gullied terrain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
5-15 new snow distributed by strong winds is making smaller, sensitive wind slabs on lee aspects. These sit on older wind pressed surfaces. Continued snow and wind will add to this problem. Most prevalent in the alpine.
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Nov 26th, 2022 4:00PM
