Avalanche Forecast
Regions: Banff Yoho Kootenay.
We are out the other side of the storms with a blast of cold and clear but slabs remained reactive to explosive control Friday. Expect a low on Saturday to stir things up again particularly as west winds start to redistribute the recent snow.
Weather Forecast
Friday night will bring overnight low temperatures approaching -20C at treeline with almost calm winds. Saturday, expect a low pressure system to affect the region as light precip starts in the morning and temps warm to -10C midday. Alpine winds will build from the southwest and may reach strong before shifting NW late in the day.
Snowpack Summary
The storms from the end of November and first days of December brought up to a meter of settled snow at treeline and periods of rain as high as 2200m. Cold temps starting Thursday afternoon froze low elevation snow. The snow from these storm sits on the Nov.15 interface (a crust below 2100m) and the Nov. 5 crust/facet layer found near the ground.
Avalanche Summary
With Thursday's clearing and avalanche control flights we have seen widespread evidence of a natural cycle up to sz 4. Many of these started as full depth avalanches in the alpine and resulted in loose wet debris piles at valley bottom. Avalanche control has produced storm slabs averaging 50-100cm deep as well as full depth slabs treeline and above
Confidence
Timing, track, or intensity of incoming weather system is uncertain on Saturday
Avalanche Problems
Storm Slabs
Soft slabs can be found treeline and above and these continued to be reactive to explosives 50 to 100cm deep Friday. More wind effect is evident in the alpine as is recent cornice development.
- If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible - Likely
Expected Size: 1.5 - 3
Deep Persistent Slabs
Explosives continued to produce slabs on the Nov 5 crust/facets Friday. Some slabs have initiated on this layer, while others were "step down" avalanches triggered as storm slabs or cornices failures hit them.
- Be aware of the potential for full depth avalanches due to deeply buried weak layers.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Possible
Expected Size: 2 - 3.5