Avalanche Forecast
Issued: Dec 10th, 2019 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
shorton,
Avalanche Canada
Resist the temptation to travel into steep or complex terrain, triggering large avalanches on buried weak layers is a concern right now.
Summary
Confidence
Moderate - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
TUESDAY NIGHT: Cloudy with some isolated flurries, 40 km/h wind from the southwest, alpine temperatures drop to -8 C.
WEDNESDAY: Cloudy with isolated flurries and up to 5 cm of new snow, 40 km/h wind from the west, alpine high temperatures around -5 C.
THURSDAY: 5-10 cm of new snow, 50 km/h wind from the west, alpine high temperatures around -2 C.
FRIDAY: Mostly cloudy, 30 km/h wind from the west, alpine high temperatures around -2 C.
Avalanche Summary
Numerous recent storm slab and persistent slab avalanches have been reported. Explosive control in the Lizard Range over the weekend produced large slab avalanches (size 2-3) at treeline and alpine elevations. The avalanches ran on the both the November and October crust layers 40-100 cm deep. Evidence of natural avalanches with wide propagation have also been reported from the Flathead area.
Fewer avalanches have been reported since the weekend, but the potential for triggering large persistent slab avalanches remains a concern.
Snowpack Summary
30-40 cm of snow from the weekend has been redistributed by the wind to form wind slabs in the alpine and near ridgetops at treeline. Crust layers from November and October can be found 40-100 cm below the surface and have recently produced large avalanches with explosive triggers. While these layers are likely widespread across the terrain, we are uncertain about whether they could also be triggered by humans. Snowpack depths range between 50-100 cm at higher elevations and taper rapidly below treeline.
Problems
Persistent Slabs
There is uncertainty about how easy (or difficult) it could be to trigger a large avalanche on one of the crusts and weak layers in the lower snowpack. Choosing conservative terrain is the best way to manage this uncertainty.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Wind Slabs
Steady wind from the west is likely forming fresh wind slabs in the alpine and near ridgetops.
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 11th, 2019 4:00PM
