Avalanche Forecast
Issued: Dec 10th, 2021 4:00PM
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.
William Lawson,
Forecasted snow and strong winds will increase the avalanche hazard at upper elevations.
Summary
Weather Forecast
A Pacific frontal low will move East to the Rockies early Saturday bringing strong Westerly winds and 15 to 30cm of snow to the forecast region by the end of the weekend. Freezing levels will remain below valley bottom.
Snowpack Summary
15-30 cm of snow overlays the Dec 2 rain crust. This crust disappears between 2100-2250 m. At treeline and above, moderate winds have developed soft slabs in immediate leeward slopes. The weak Nov 5 crust/facet interface is present near the ground. We expect further wind slab development at upper elevations through the day Saturday.
Avalanche Summary
No new avalanche activity observed or reported Friday. Forecasted snow and strong winds Saturday will likely increase natural avalanche activity at upper elevations.
Confidence
Problems
Loose Dry
Strong winds and 15 to 30cm of new snow will provide ideal conditions for loose dry avalanches in steep terrain. Though relatively small in size these avalanches could have serious consequences when traveling in a gullies features or above cliffs.
- Use caution above cliffs and terrain traps where small slab avalanches may have severe consequences.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
We will see an increase in wind slab development on Alpine and tree line lee slopes Saturday. The size and sensitivity of these new slabs will depend on local snow available for transport.
- Be careful with wind loaded pockets while approaching and climbing ice routes.
- Minimize overhead exposure during periods of heavy loading from new snow, wind.
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
We continue to see occasional high consequence avalanches on the Nov 5 crust/basal facets in specific terrain features. Some slabs have initiated on this layer, while others were "step down" avalanches triggered as wind slabs or cornices hit them.
- Be aware of the potential for full depth avalanches due to deeply buried weak layers.
- Avoid steep convexities or areas with a thin or variable snowpack.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 11th, 2021 4:00PM
