Avalanche Forecast
Issued: Dec 11th, 2021 5:42PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Loose Dry, Wind Slabs and Deep Persistent Slabs.
Conrad Janzen,
New snow and strong winds have increased the avalanche hazard at all elevations for Sunday.
Summary
Weather Forecast
This storm should bring another 10-15 cm overnight before moving out of the region early Sunday morning with only light flurries remaining. Temperatures will drop following the storm. Expect to see highs of -12 to -15 C at treeline on Sunday. Wind speeds will also drop into the moderate range out of the SW in most areas with some strong gusts.
Snowpack Summary
Up to 15 cm of new snow Saturday with more expected overnight. 25-45 cm of snow now overlays the Dec 2 crust which is present up to 2100-2250 m. At treeline and above, strong to extreme W & SW winds have developed slabs in lee areas with extensive wind effect in open areas. The weak Nov 5 crust/facet interface is present near the ground.
Avalanche Summary
Several skier and explosive controlled wind slab avalanches up to size 2 were reported by the local ski areas along with some smaller dry loose avalanches. A few other reports of small skier triggered wind slabs and natural sluffing in steep terrain were also received.
Confidence
Timing, track, or intensity of incoming weather system is uncertain
Problems
Loose Dry
15 to 30 cm of new snow will provide ideal conditions for loose dry avalanches in steep terrain, including below treeline where the new snow sits on the slippery Dec 2 crust. Natural activity will slow with less wind but is still possible.
- If triggered dry loose point releases can form deeper deposits in terrain traps.
- Be careful of loose dry sluffing in steep, confined or exposed terrain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Strong winds and new snow have created fresh wind slabs in exposed terrain at treeline and above, and extensive wind effect in open areas. It will probably be fairly easy to trigger these slabs in steep wind loaded terrain on Sunday.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- Watch for shooting cracks or stiffer feeling snow. Avoid areas that appear wind loaded.
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
The new snow load may increase the likelihood of avalanches on the Nov 5 crust/basal facets for a few days. Steep shallow snowpack areas, cross loaded rocky terrain and areas exposed to large triggers such as cornices are the most concerning.
- Avoid steep convexities or areas with a thin or variable snowpack.
- Be aware of the potential for full depth avalanches due to deeply buried weak layers.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 12th, 2021 4:00PM
