Avalanche Forecast
Issued: Jan 20th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Cornices.
JSmith,
Avalanche Canada
Recent snow and extreme southwesterly winds have created touchy wind slabs in many locations, even open areas below treeline. Use caution when transitioning into wind affected terrain.
Summary
Confidence
Moderate - Uncertainty is due to the limited number of field observations. Uncertainty is due to extremely variable snowpack conditions reported through the region.
Weather Forecast
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WEDNESDAY NIGHT: Clearing / Light, northwest ridgetop wind / alpine low temperature -16 / Freezing level valley bottom.
THURSDAY: Mostly sunny / Light, northwest ridgetop wind / alpine high temperature -10 / Freezing level valley bottom.
FRIDAY: Mix of sun and cloud / Light, northwest ridgetop wind / alpine high temperature -12 / Freezing level valley bottom.
SATURDAY: Cloudy / Moderate, west ridgetop wind / alpine high temperature -12 / Freezing level valley bottom.
Avalanche Summary
On Tuesday, our field team reported widespread wind effect at all elevations, creating fragile cornices and reactive wind slabs on north and east facing slopes below ridgetops. MIN report HERE.
On Monday our field team observed some size 2 natural avalanches on a north facing alpine feature east of Crescent Spur. These likely ran over the weekend.
On Sunday we received some great observations of avalanches running naturally on a crust in the trees in "The Farm" area, more details here.
Snowpack Summary
30-50 cm of recent snow and extreme southwest winds have created large, fragile cornices and widespread wind slabs in many locations, even open areas below treeline.
Underneath the recent snow you are likely to find a hard melt-freeze crust that can be found up to about 1600 m. You may also find a weak layer of buried surface hoar in isolated, sheltered locations below treeline. As the new snow continues to settle and form slab properties, these layers could become reactive to human traffic.Â
Around 60 to 130 cm of snow rests above another weak layer buried in early-December. On Jan 14th our field team found it in the Holmes area. This setup has created a persistent slab avalanche problem and a low probability/high consequence scenario. Depending on location, the buried weak layer is composed of surface hoar and/or a crust/facet combination. Reports suggest that this layer has become dormant in much of the region except for perhaps the Pine Pass area.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Avoid lee and cross-loaded terrain.
- Cornices become weak with daytime heating or solar exposure.
- Avoid exposure to slopes that have cornices overhead.
- Cornices often break further back than expected; give them a wide berth when traveling on ridgetops.
Problems
Wind Slabs
Recent snow and extreme southwesterly winds have created touchy wind slabs in many locations, even open areas below treeline.
Aspects: North, North East, East, South East, North West.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Recent snow and extreme winds have formed large and fragile cornices that could trigger large avalanches when they fail. Avoid traveling under cornices during periods of intense sunshine.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine.
Likelihood
Expected Size
Valid until: Jan 22nd, 2021 4:00PM
