Avalanche Forecast
Issued: Jan 19th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
swerner,
Avalanche Canada
Reactive wind slabs may build on Thursday with new snow, strong wind and warmer temperatures.
Be mindful of the lingering deep persistent slab problem. Caution on shallow snowpack areas and thin to thick steep rocky zones.
Summary
Confidence
Moderate - Forecast snowfall amounts are uncertain.
Weather Forecast
Thursday Night: Increasing cloud cover later in the evening with some new snow forecast up to 5 cm. Ridgetop wind light from the southwest and alpine temperatures near -10.Â
Thursday: Snow 5-10 cm accompanied by moderate ridgetop wind from the southwest. Alpine temperatures warming to near -5 and freezing levels 1200 m.
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Friday: Mostly cloudy with ridgetop winds moderate from the West. Alpine temperatures near -5 and freezing levels valley bottom.
Saturday: Potential for inversion with valley cloud and cooler temperatures down low and sunshine in the alpine. Alpine temperatures near -3 and below freezing in the valleys.
Avalanche Summary
On Wednesday, no new avalanches were reported in the region.
A wind slab avalanche was released naturally on steep north-facing wind-loaded alpine terrain on Tuesday on Lizard Peak.
A near-miss happened this weekend on Tombstone mountain when a rider triggered a large persistent slab and got completely buried. Luckily, the airbag helped keep the victim's head above the snow. This evidence suggests the deep persistent slab problem is still a concern in the region.
Snowpack Summary
5 cm of new snow fell overnight with an additional 10 cm in the forecast. This sits above older wind-affected and crusty surfaces. Around 2000 m and below, a crust is now capping the dense 15 to 30 cm of snow which has settled significantly with the past mild temperatures. The crust varies from thin/breakable to thick/supportive, according to the aspects and elevation. The midpack is well consolidated.Â
The most notable layer of concern in the snowpack is a crust that was formed in early December and is now down 100-270 cm. This layer was last reactive on Thursday, Jan 13 with warming and solar radiation. This layer has created a low likelihood, high consequence scenario which is best managed through conservative terrain choices and disciplined backcountry travel techniques.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Watch your sluff: it may run faster and further than you expect.
- In areas where deep persistent slabs may exist, avoid shallow or variable depth snowpacks and unsupported terrain features.
- Be aware of the potential for large avalanches due to the presence of a deep persistent slab.
Problems
Wind Slabs
The new snow accompanied by strong winds and slight warming on Thursday may form new and reactive wind slabs. They potentially could have a poor bond to the crusty snow surfaces.
Dry loose sloughing may be seen from steeper slopes and terrain features.
Aspects: North, North East, East.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
A deep persistent slab problem formed by a crust down 100-270 cm has created a low likelihood, high consequence scenario that is difficult to forecast. There has been an increase in avalanche reports on this deep layer over the last week. This problem is likely to be triggered on steep, rocky slopes with a shallow or thin-to-thick snowpack. The same feature or path can slide repeatedly when the persistent weak layer is reloaded with new snow.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Jan 20th, 2022 4:00PM
