Avalanche Forecast
Issued: Dec 9th, 2019 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
ldreier,
Avalanche Canada
The snowpack structure is unusually shallow and weak for this region. Highly variable thickness of windslab allows for triggering avalanches from thin spots.
Summary
Confidence
Weather Forecast
MONDAY NIGHT: Cloudy with clear periods, light wind from the southwest, alpine temperatures around +3 C, freezing level at 2600 m with a weak temperature inversion.
TUESDAY: Cloudy with flurries, up to 5 cm of snow, 50 km/h wind from the southwest, alpine high temperatures around -2 C, freezing level lowering to 1100 m.
WEDNESDAY: Cloudy with flurries, 50 km/h wind from the south, alpine high temperatures around -4 C, freezing level at 1000 m.
THURSDAY: Cloudy, 20-40 cm of snow, 40 km/h wind from the southwest, alpine high temperatures around -4 C, freezing level at 1000 m.
Avalanche Summary
On Sunday, a few natural and skier triggered slab avalanches of size 1-2 were observed. Several explosive triggered slab avalanches and cornices to size 1-2 were reported. The cornices triggered small slabs on the slopes below which were up to 30 cm thick and ran on a facet/crust layer.
On Saturday, several natural avalanches up to size 2 were reported. A small slab avalanche (size 1.5) was triggered remotely by skiers on an unsupported north facing slope in the alpine. It was 20-30 cm thick.
Snowpack Summary
Strong southerly winds transported the recent storm snow. This new snow layer is 10 - 70 cm thick depending on the amount of wind affect. Underneath this new snow is a hard crust that formed in late November. The snow above this crust is weak and provides a bed surface for avalanches to run on. Recent snowpack tests have shown notable results on this facet/crust layer. Whumpfing and shooting cracks were reported in the alpine. The snowpack we are seeing at the moment is unusually shallow and weak for the Sea to Sky region.
Currently, typical snowpack depths in the alpine range between 50 and 180 cm, depending on the amount of wind affect. Snowpack depths taper quickly with elevation as most below treeline terrain is still below the threshold for avalanches.
Problems
Wind Slabs
Strong wind from the south transported the recent storm snow and created wind slabs which are 10-70 cm thick depending on the amount of wind affect. The recent storm sits on a weak facet/crust layer. The current snowpack is unusually shallow and weak for this region. Together with a highly variable thickness of the windslab there is the potential of hitting a thin spot and triggering a connected slab.
Cornices have formed with the strong wind and if they fail their load can trigger avalanches on the slopes below.
Aspects: North, North East, East, West, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Dec 10th, 2019 5:00PM
