Avalanche Forecast
Issued: Dec 8th, 2020 8:12AM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Deep Persistent Slabs.
Chris Gooliaff,
The storm came in heavy and warm, and now we are in a natural avalanche cycle.
Avoid any overhead hazard today as we expect avalanches to be running all the way into the valley bottoms.
Summary
Weather Forecast
One more storm day, then the weather eases into slightly cooler, sunnier conditions.
Today: Periods of snow, 10-15cm. FZL 1500m, wind SW-25-40km/h
Tonight: Isolated flurries, FZL dropping to 1200m, wind W 10-25km/h
Wed: Mix of sun/cloud, FZL 900m, light W winds
Thurs: mix of sun/cloud, FZL 500m, light W winds
Snowpack Summary
30+cm of warm snow and mod/strong SW winds have created a storm slab. It sits on a significant widespread surface hoar (SH) layer at tree-line and lower elevations. In the alpine, the storm slab rests on a crust on steep solar aspects. Several SH layers exist in the mid-upper pack, while the Nov 5 crust lurks as a deep persistent weakness.
Avalanche Summary
There is an ongoing natural avalanche cycle to sz 3 affecting all elevation bands.
Confidence
Problems
Storm Slabs
The warm, heavy new snow has created a cohesive 25-40cm storm slab. It sits on widespread surface hoar (SH) or on a crust on steep solar aspects. Locations of large SH will be particularly touchy (below tree-line).
- Be aware of the potential for wide propagations.
- Watch for signs of instability such as whumpfing, or cracking.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Deep Persistent Slabs
The heavy storm slab may stress the snowpack enough to trigger this deep persistent slab. If avalanches step down to this layer, expect to see very large avalanches running into the valley bottom.
- Avoid shallow snowpack areas where triggering is more likely.
- If triggered the storm slabs may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 9th, 2020 8:00AM
