Avalanche Forecast
Issued: Dec 18th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Storm Slabs and Persistent Slabs.
zryan,
Avalanche Canada
Heavy snowfall and strong winds over the past 24 hours have created dangerous avalanche conditions. It's a great day to head to the ski resort and give the snowpack time to adjust to a large amount of new load.
Summary
Confidence
Moderate - Forecast precipitation (either snow or rain) amounts are uncertain. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
Saturday Overnight: Snowing, heavy at times with another 15-30cm of accumulation. Strong southwest winds will ease to light and shift to the west by the morning. Freezing levels dropping to valley bottom with alpine temperatures around -10 C.
Sunday: Partially cloudy with isolated flurries in the wake of the front. Light westerly winds with alpine temperatures around -12 C.Â
Monday: Mainly cloudy with flurries, trace to 5cm of accumulation. Winds increasing throughout the day, moderate to strong west winds at ridgetop by end of day. Alpine temperatures around -10 C.
Tuesday: Partially cloudy with moderate to strong westerly ridgetop winds and light flurries. Alpine temperatures around -10 C.
Avalanche Summary
On Saturday, operators reported numerous size 1-2 loose dry and storm slab avalanches.
On Friday, operators reported several size 2.5 natural and cornice triggered storm slab in the alpine. Numerous explosives' and ski cutting results both loose dry and storm slab where observed up to size 2.Â
On Friday, several natural slab avalanches where reported in the backcountry adjacent to Fernie Alpine Resort, with one notable persistent slab failing on the early December crust.
Snowpack Summary
An intense storm came through the region yesterday, bringing 40-60 cm of new snow. Storm slabs are expected to be widespread across aspects and elevations. In exposed areas in the alpine and treeline, strong southwest winds will have created deeper deposits in lee areas.Â
Below this new snow, consolidated snow from the previous weekend storm sits over a substantial crust that formed in early December. This crust is likely 20 cm thick (or more) and is present across aspects below 2400m. A thin layer of weak facets (sugary snow) can found above this crust.Â
The lower snowpack consists of a mix of various early season crusts and mainly moist snow. Snowpack depths range from 55-170 cm at treeline elevations and taper quickly below 1800 m.
Terrain and Travel
- Stick to simple terrain and be aware of what is above you at all times.
- Continue to make conservative terrain choices while the storm snow settles and stabilizes.
- Storm slabs in motion may step down to deeper layers resulting in large avalanches.
Problems
Storm Slabs
40-60 cm of new snow has fallen since Friday evening. The new snow will likely form a reactive storm slab problem across all aspects. In areas where the new snow is not forming a slab, it will react as a touchy loose dry problem. Anticipate larger, more reactive slabs in wind-drifted areas.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Persistent Slabs
A layer of weak facets (sugary snow) can be found down 80-150 cm over a crust that formed in early December. This layer is starting to produce avalanches across the province and this storm may be the tipping point to start seeing both natural and human triggered large destructive avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 19th, 2021 4:00PM
