Avalanche Forecast
Issued: Dec 14th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs and Wind Slabs.
bchristie,
Avalanche Canada
Adopt a conservative approach to choosing terrain, and avoid thin, rocky start zones. The snowpack appears to be gaining strength, but some persisting weak layers could still be reactive to a rider's weight.
Summary
Confidence
Weather Forecast
The upcoming weather is fairly uneventful. Clouds and light snowfall will be in and out, and the alpine winds will pick up a bit near the end of the week.
TUESDAY NIGHT: Partly cloudy. 0-2cm of snow expected. Light to moderate southwest winds, trending to strong northwest in the alpine. Freezing level dropping to valley bottom.
WEDNESDAY: Scattered clouds. Possible trace of snow expected. Light to moderate southwest winds, trending westerly at higher elevations. Alpine temperatures around -13.
THURSDAY: Partly cloudy. Possible trace of snow. Light to moderate southwest winds, with strong to extreme westerlies on higher peaks. Alpine high around -8.
FRIDAY: Scattered clouds. No new snow expected. Light west winds trending to moderate southwest, and strong northwest in the alpine. Alpine temperatures around -11 with a possible temperature inversion setting up.
Avalanche Summary
No new natural avalanches observed.
Avalanche control on Tuesday produced mostly small results on lingering hangfire from Monday's avalanche control. One size 2 explosive triggered avalanche was reported in previously unopened terrain.
This MIN Report paints a good picture of the avalanche problem right now. They spotted a natural avalanche in a wind loaded feature, and whumpfing in shallow areas.
Reports indicated that the snowpack was quite touchy this weekend. Avalanche control with explosives and ski cuts produced several size 2 avalanches, and one size 3. Most failed on top of the rain crust from the late November/early December rain events.
Snowpack Summary
Yesterday's snow fell with very little wind, so it should be mostly unconsolidated. Where this new snow has been wind transported, (most likely at higher elevations) it could still form reactive slabs.
Moderate to strong southwest winds during the last storm formed wind slabs that seem to be starting to bond to the early December rain crust, but we're not entirely ready to trust it. This interface was recently active, and a thick crust like this is more likely to encourage faceting.
Snowpack depths are extremely variable due to strong to extreme southwest winds from early December that stripped snow off of exposed areas, and made deep drifts in lee slopes.
Below 2300m, several early season crusts are breaking down and forming a cohesive lower snowpack.
Snowpack depths range from 60-110 cm at treeline elevations. The snowpack tapers quickly below 1900m.
Terrain and Travel
- Use conservative route selection and resist venturing out into complex terrain.
- Be careful with open slopes and convex rolls, especially in more extreme terrain.
- Be aware of the potential for large avalanches due to the presence of a persistent slab.
Problems
Persistent Slabs
Southwest of Pincher Creek, avalanche control has produced explosive and skier triggered avalanches on this layer.
This crust is widespread across the province, and many operations have been watching it for signs of reactivity as the load on top of it increases. It may also get more reactive as cold temperatures promote faceting above the crust.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Wind Slabs
Moderate to strong southwest winds have formed the recent storm snow into slabs that are deeper and more reactive in leeward features.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 15th, 2021 4:00PM
