Avalanche Forecast
Issued: Dec 29th, 2020 8:00AM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs, Loose Dry and Persistent Slabs.
Jonas Hoke,
We currently have a complex snowpack with persistent weak layers that could produce high consequence avalanches if you were unlucky enough to trigger them.
Be particularly cautious on open slopes with a crust at the Dec. 7th weak interface.
Summary
Weather Forecast
High pressure will give stable weather for one more day. A frontal system arriving from the Northwest will give increasing wind and steady snowfall Wednesday.
Today: Mix of sun and cloud. Alpine High -8 C. Ridge wind light SW.
Tonight: Cloudy with isolated flurries. Alpine Low -10 C.
Wednesday: Snow (15cm). High -8 C. Ridge wind moderate-strong SW.
Snowpack Summary
Up to 25cm of recent snowfall is being stiffened into a slab in some wind exposed areas. This new snow covers spotty surface hoar in sheltered areas at and below treeline. Weak layers persist down 70-110cm (Dec 13 surface hoar), and 110-130+cm (Dec 7 crust/facte/surface hoar). The Nov. 5th crust complex is near the base of the snowpack.
Avalanche Summary
There were MIN reports of skiers triggering loose dry avalanches up to size 2 in steep terrain, and one small storm slab in an immediate lee at treeline.
There was a natural size 2.5 storm slab from steep North facing terrain on Mt Macdonald.
Several very large avalanches last week failed on the early December crust, facet/surface hoar combo.
Confidence
Problems
Storm Slabs
Watch for pockets of storm slab in immediate lees Tuesday. Expect this problem to become more widespread and destructive with Wednesdays snow and wind.
- Watch for stiffer feeling snow. Avoid areas that appear wind loaded.
- Use safe ski cutting techniques to enter your line.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Loose Dry
Slough management is necessary on steeper, open slopes. Loose dry slides are gathering enough mass to push a skier or rider over, or even bury one in a terrain trap.
- If triggered dry loose point releases can form deeper deposits in terrain traps.
- Be careful of loose dry power sluffing in steep terrain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
The Dec 7th and Dec 13t layers produced very large avalanches last week, up to size 4! One of these very large avalanches, from a South aspect at Treeline, had the Dec 7th interface as the failure plane which consisted of a crust with facets above.
- Be wary of large open slopes that did not previously avalanche.
- Carefully evaluate terrain features by digging and testing on adjacent, safe slopes.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Dec 30th, 2020 8:00AM
