Avalanche Forecast
Issued: Dec 8th, 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
Low - Uncertainty is due to the complexity of the snowpack’s structure. Uncertainty is due to how quickly the snowpack will recover and gain strength.
Weather Forecast
SUNDAY NIGHT: Clear, 30 km/h wind from the north, alpine temperature around 0 C with a weak temperature inversion, freezing level at 2200 m.
MONDAY: Mainly sunny, light wind from the northwest, alpine high temperatures around +2 C with a weak temperature inversion, freezing level at 2700 m.
TUESDAY: Cloudy with isolated flurries, 40 km/h wind from the southwest, alpine high temperatures around -2 C, freezing level at 1100 m.
WEDNESDAY: Cloudy with flurries, 50 km/h wind from south, alpine high temperatures around -4 C, freezing level at 1000 m.
Avalanche Summary
On Sunday, a few avalanches of size 1 and size 2 were remotely triggered by skiers. Several size 2 and small (size 1) slab avalanches and cornices were triggered with explosives.Â
On Saturday, a small slab avalanche (size 1.5) was triggered remotely by humans on an unsupported slope on a northern aspect in the alpine. It was 20-30 cm thick. Several natural avalanches up to size 2 were reported.
On Wednesday, a few small (size 1) slab avalanches were triggered by skiers and explosives. They were 20-30 cm thick and ran on a hard crust.
Snowpack Summary
Strong southerly winds transported the recent storm snow. This new snow layer is 10 - 50 cm thick depending on the amount of wind affect. The new snow is heavy due to the warm temperatures. Not too far beneath 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 10-50 cm thick depending on the amount of wind affect. The recent storm snow is heavy due to the warm temperatures and 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. Warm alpine temperatures will increase the likelihood of these cornices to fail. 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 9th, 2019 5:00PM
