Avalanche Forecast
Issued: Dec 1st, 2020 4:47PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
Lisa Paulson,
Climbers/skiers take note - the upper elevation temperatures rise to +5C tonight & Wednesday causing a bump up in hazard. We expect increased avalanche activity, particularly on steep solar aspects.
Summary
Weather Forecast
Tonight a temperature inversion establishes with temperatures at 2000 m and above rising to +5C tonight and through tomorrow. The rise in temperature together with sunny skis will cause existing layers to become more sensitive to triggering or produce natural avalanches on Wednesday. Temperatures will cool Thursday late afternoon.
Snowpack Summary
Variable surface conditions exist with hard wind slabs in exposed locations and softer snow in more sheltered areas. The Nov 5 facet/crust combo is down 50-80 cm and producing variable test results, but can be 'sudden' in character. This crust extends up to 2500 m on N aspects and higher on solar aspects. Snow depths at treeline are 70-130 cm.
Avalanche Summary
No avalanche activity reported Tuesday. There have been a few isolated larger avalanches in the last week on deeper layers including a size 2.5 avalanche on the W aspect of Dolomite Peak on Sunday in a cross loaded gully feature and a couple deep avalanches on steep glacier features. Warm air aloft & sunny skies Wed may cause activity to increase.
Confidence
Problems
Wind Slabs
Wind slabs exist in exposed alpine areas from strong winds over the past week. Slabs may be more reactive with warmer temperatures and sun exposure if you are in steep lee loaded or cross loaded terrain.
- Be careful with wind loaded pockets, especially near ridge crests and roll-overs.
- If triggered the wind 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 Nov 5 crust has facets growing above and below it, and exists up to 2500m on shady aspects and higher on solar aspects. We have seen a few isolated avalanches on this layer so use caution in large steep terrain features.
- Pay attention to overhead hazards like cornices which could trigger the deep persistent slab.
- Be aware of thin areas that may propogate to deeper instabilites.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 2nd, 2020 4:00PM
