Avalanche Forecast
Issued: Dec 22nd, 2021 3:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Deep Persistent Slabs.
Dnylen,
Avalanche Canada
It is easiest to trigger avalanches in areas that look deep with heavy surface snow. Cold temperatures can make wind slabs last longer than usual.
Summary
Confidence
Moderate - Uncertainty is due to limitations in the field data.
Weather Forecast
Winds decreasing but still moderate at ridge top. The cold continues!
WEDNESDAY NIGHT: Overnight low temperature -22, moderate north wind, strong at ridge top. Mostly clear. No new snow expected.
THURSDAY: Mostly clear, daytime high temperature around -21, Light variable wind at valley bottom, strong north wind at ridge top, possible flurries to 2cm
FRIDAY: Broken cloud cover, daytime high temperature around -21, moderate to strong north/northwest wind, no new snow
SATURDAY: mostly clear, daytime high temperature around -31, moderate north wind, no snow expected.
Avalanche Summary
On Wednesday our field team observed several natural avalanches up to size 2 in the White Pass on east and southeast aspects in the alpine and treeline.
This MIN from Monday reported shooting cracks and other signs of instability in Fraser Chutes at treeline.Â
Snowpack Summary
10-20cm of recent snow has been heavily re-distributed by strong north winds. These fresh wind slabs will be touchy at first and cold temperatures can keep them sensitive for longer.
On the weekend two MIN reports here & here mention surface hoar at and below 1300m, which could be buried just below the recent windslab.
The middle snowpack is supportive to travel but snow depth still varies greatly with aspect and elevation.Â
The lower snowpack is made up of weak sugary snow. An avalanche at this interface is most likely to be triggered in shallow areas or with a large impact like a cornice fall or surface avalanche.
Terrain and Travel
- Be aware of highly variable recent wind loading patterns.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Stay off recently wind loaded slopes until they have had a chance to stabilize.
Problems
Wind Slabs
Alpine wind slabs may be further down the slope than normal and very hard. Cold temperatures can make it possible to trigger them for longer. At and below 1300m these may be sitting on buried surface hoar which could result in larger than expected avalanches.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Most likely trigger points are areas where the snowpack goes from thin to thick, such as rock outcroppings. A large trigger like a cornice fall or avalanche in motion could potentially activate this deep persistent slab.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 23rd, 2021 3:00PM
