Avalanche Forecast
Issued: Dec 8th, 2019 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
aaron beardmore,
Parks Canada
The Nov crust/facet layer is becoming reactive and was the sliding layer in several large avalanches across the forecast region today. Although natural activity has tapered, human triggering remains real.
Summary
Weather Forecast
Continued NW wind in the moderate range is expected overnight. Temperatures should remain seasonal in the -10 range. Minimal snow and mixes of sun and cloudy periods for the next few days.
Snowpack Summary
40-60+ cm of snow has fallen in the last 4 days. A storm slab has formed at treeline and above. Below the storm slab, the snowpack structure is generally weak, consisting of facets and depth hoar. The Nov crust exists up to 2500m and 30 cm up from ground. Snowpack depths at treeline are 80-130 cm and deeper in lee areas.
Avalanche Summary
A skier accidental size 2.5 was reported in West Bowl at Lake Louise today. The snowboarder was able to ride off to the side. This avalanche slid on the Nov crust layer. Sunshine Patrol also reported some very large explosive controlled avalanches in the Delirium Dive today up to size 3. These slides also ran on the Nov layer.
Confidence
Due to the number and quality of field observations on Sunday
Problems
Storm Slabs
40-60 cm of recent snow and wind have formed a storm slab in many open areas at treeline and in the alpine. Human triggering of this slab will remain likely though natural avalanche activity will slow down.
- Use caution 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: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
As of today, large avalanches were reported as initiating on the Nov crust/facet layer and stepping down and gouging to near ground. Some were triggered with large loads (explosives) and one was triggered by a snowboarder on an adventure.
- Be aware of thin areas that may propogate to deeper instabilites.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 9th, 2019 4:00PM
