Avalanche Forecast
Issued: Dec 21st, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
jleblanc,
Avalanche Canada
Reactive wind slabs are our main concern with the current storm. Seek out sheltered terrain where the snow has not been wind-affected to find great riding.
Summary
Confidence
High - We are confident the likelihood of avalanche will increase with the arrival of the forecast weather.
Weather Forecast
A low-pressure system over the Gulf of Alaska will slide southwards Tuesday. Moderate snow will intensify Tuesday afternoon throughout Wednesday, especially in the Northern part of the region. Arctic air will return late Thursday, with bitterly cold and drier conditions for the weekend.
TUESDAY NIGHT: Snow 5 cm / Strong west wind / Low of -12 at 2000 m.
WEDNESDAY: Snow 15-20 cm / Strong to extreme southwest wind / High of -7 at 2000 m.
THURSDAY: Flurries / Moderate west wind / High of -14 at 2000 m.
FRIDAY: Cloudy / Moderate southwest wind / High of -18 at 2000 m.
Avalanche Summary
Few natural dry loose avalanches were reported out of steep terrain (size 1). Old avalanche debris from the last storm were seen but no recent signs of avalanche activity. Â
With the next storm, expect to see natural avalanches in specific areas.Â
If you go out in the mountains, please consider filling out a Mountain Information Network report.
Snowpack Summary
Strong alpine wind affected the recent storm snow (20-40 cm) in upper elevation, while cold temperature in the valley was prone to develop weak surface snow grains (surface hoar).
A facet/crust layer, developed in early December, is now buried between 60-100 cm down. This layer generally exists below 1800 m and is most concerning in the area west of Blue River. In some places, the crust starts to decompose and show sporadic test results.
Terrain and Travel
- Stay off recently wind loaded slopes until they have had a chance to stabilize.
- Fresh wind slabs will likely form throughout the day, diligently watch for changing conditions.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Wind Slabs
New snow to come (15-25 cm) and hauling winds (up to 60 km/h) will rapidly create touchy wind slabs on alpine lee features and open areas at treeline. As wind slabs are more reactive to human triggers during their formation, seek out sheltered terrain where the snow has not been wind-affected.
Aspects: North, North East, East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer of facets can be found above a crust from early December, which is now down 80 to 150 cm and most concerning in the terrain West of Blue River at the treeline elevation. Although this persistent weak layer showed sporadic and various test results, keep in mind that the incoming storm may increase the likelihood of triggering it.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Valid until: Dec 22nd, 2021 4:00PM
