Avalanche Forecast
Regions: North Rockies.
There is lots of new snow available for the wind to redistribute into lee terrain. As a result wind slabs at upper elevations will be the main concern when the wind speed picks up.
Confidence
Moderate - Uncertainty is due to limitations in the field data.
Weather Forecast
Friday Night: Mostly cloudy with some clear periods. Light to moderate southwest wind. Freezing level valley bottom. Alpine temperature -8.Â
Saturday: Mostly cloudy with scattered flurries, accumulation 2-5 cm. Light to moderate southwest wind. Freezing level 1200 m. Alpine temperature -4.
Sunday: Partly cloudy. Moderate to strong west wind. Freezing level 1400 m. Alpine temperature -3.
Monday: Mostly cloudy. Moderate southwest wind. Freezing level 1500 m. Alpine temperature -2.Â
Avalanche Summary
There are no recent reports of avalanche activity, although with recent snow and wind there is likely natural wind slab activity at upper elevations.
Evidence of large storm slab avalanches (size 3) was observed Monday and Tuesday between Sentinel Pass and Chetwynd, likely having released during the storm on the weekend.
Snowpack Summary
10-40 cm of recent snow earlier in the week has been redistributed by strong southwest to northwest wind with wind slabs possible on many aspects and large, fragile cornices along ridgetops. This snow sits on melt freeze crusts at lower elevations and on solar aspects.Â
A weak layer of facets buried in mid-February may now be found around 120 to 150 cm deep, or shallower in the east of the region and in thin snowpack areas. The most likely place to trigger this layer is where the snowpack is shallow in alpine terrain. Large loads, such a cornice falls or multiple sleds on the same slope often trigger slopes that a single rider couldn't trigger on their own.
Terrain and Travel
- Be careful with wind slabs, especially in steep, unsupported and/or convex terrain features.
- Be aware of highly variable recent wind loading patterns.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
Avalanche Problems
Wind Slabs
Flurries bringing small amounts of new snow will feed fresh wind slab development. Variable wind direction has resulted in deep pockets of recent storm snow on a variety of aspects. These older wind slabs are likely becoming more difficult to trigger.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Possible
Expected Size: 1 - 2
Persistent Slabs
The persistent slab problem is most likely on the eastern slopes of the region (e.g., Kakwa, Tumbler Ridge) and in areas where the snowpack is thin. Steep, rocky slopes with a shallow or thin to thick snowpack in the alpine are the most likely places to trigger buried weak layers. This problem likely won't go away until a substantial melt-freeze cycling occurs.
Aspects: All aspects.
Elevations: Alpine.
Likelihood: Unlikely - Possible
Expected Size: 2 - 3