Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches unlikely, human triggered possible.
Below Treeline
Natural avalanches unlikely, human triggered possible.
Alpine
Natural avalanches possible, human triggered probable.
Treeline
Natural avalanches possible, human triggered probable.
Below Treeline
Natural avalanches possible, human triggered probable.
Regions
Northwest Coastal.
The recent storm snow will need time to settle and may be reactive to rider triggers. Storm slab avalanches could step down and trigger deeper layers within the snowpack, initiating large avalanches.
Confidence
Low - Due to the number and quality of field observations
Weather Forecast
Saturday: Mix of sun and cloud with isolated flurries and alpine temperatures near -10. Ridgetop winds light from the North West and freezing levels at valley bottom.Sunday: Mix of sun and cloud. Alpine temperatures near -8 and freezing levels at valley bottom. Ridgetop winds light from the West.Monday: Cloudy with 10-25 mm of precipitation. Ridgetop winds moderate from the South West. Alpine temperatures rising to 0 degrees and freezing levels near 1200 m.
Avalanche Summary
On Thursday, reports indicate natural slab avalanche activity up to size 2 from steep alpine features and numerous loose dry size 1 avalanches from steep terrain at all elevations. Please consider submitting your observations this weekend to the Mountain Information Network.
Snowpack Summary
Recent accumulated storm snow amounts are from 100-130cm and sit on a supportive 5-10 cm thick crust that was buried a week ago. The new snow seems to be settling quickly, however; deeper deposits of wind slab may be found on leeward slopes. Digging deeper in the snowpack exists a crust/facet combo buried at the end of October. This crust may exist anywhere from 90 cm-150 cm down. Recent snowpack test results are showing hard compression tests with sudden collapse results. I would keep this on my radar through the weekend to see how the snowpack adjusts to the new load.
Problems
Storm Slabs
Storm Slab avalanches are the release of a cohesive layer (a slab) of new snow that breaks within new snow or on the old snow surface. Storm-slabs typically last between a few hours and few days (following snowfall). Storm-slabs that form over a persistent weak layer (surface hoar, depth hoar, or near-surface facets) may be termed Persistent Slabs or may develop into Persistent Slabs.
Deep Persistent Slabs
Deep Persistent Slab avalanches are the release of a thick cohesive layer of hard snow (a slab), when the bond breaks between the slab and an underlying persistent weak layer deep in the snowpack. The most common persistent weak layers involved in deep, persistent slabs are depth hoar or facets surrounding a deeply buried crust. Deep Persistent Slabs are typically hard to trigger, are very destructive and dangerous due to the large mass of snow involved, and can persist for months once developed. They are often triggered from areas where the snow is shallow and weak, and are particularly difficult to forecast for and manage.