Avalanche Forecast
Issued: Nov 17th, 2019 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
Conrad Janzen,
Parks Canada
Fresh wind loading and mild temperatures on Monday mean that skier triggering of small loaded pockets, or steep areas with weak facets near the ground, can still be skier triggered. Some solar triggered sluffing may also occur if the sun comes out.
Summary
Weather Forecast
The winds will remain out of the West but start to ease off on Monday with a clearing trend in the morning. Temperatures remain quite mild with valley bottom temperatures above freezing during the day. Flurries are expected later in the day with accumulations of only a couple cm's.
Snowpack Summary
5-10 cm of new snow with warm temps and strong SW winds is loading lee areas and building cornices. 10-25 cm of settled snow sits over the Nov 8 crust. Faceting observed near the ground and around the Oct crust, resulting in easy test results in some areas. Treeline snow depths range from 50-80 cm, with up to 110 cm in wind loaded alpine areas.
Avalanche Summary
On Sunday local ski hills reported ski cutting in alpine lee areas to size 1, and an explosive controlled size 2 on facets near the ground at Lake Louise. No natural avalanche observations but visibility was limited. The skier accidental size 2 on basal facets in Pipestone Bowl on Friday is worth remembering as the snow load slowly increases.
Confidence
Freezing levels are uncertain on Monday
Problems
Wind Slabs
We did not receive as much snow as forecast (or hoped for) on Sunday, however there is new wind loading going on in alpine and open treeline areas with strong SW winds. This will result in small slabs that can be skier triggered.
- Use caution in lee areas in the alpine and treeline. Storm snow is forming reactive slabs.
- If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
The basal facets and Oct crust have been most reactive in the Lake Louise area, but it is likely that similar pockets exist throughout the forecast area. Keep watching for weak areas at the base of the snowpack, especially in steep or convex terrain.
- Convex features and steep unsupported slopes will be most prone to triggering.
- Be aware of the potential for full depth avalanches due to weak layers at the base of the snowpack.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Nov 18th, 2019 4:00PM
