Avalanche Forecast
Issued: Dec 11th, 2021 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.
ghelgeson,
Avalanche Canada
Recent storm snow and wind have combined to form slabs in wind exposed terrain that will likely remain sensitive to human triggering Sunday. Craft travel plans that keep you in wind sheltered zones and don't linger in avalanche paths.
Summary
Confidence
Weather Forecast
We’re slowly moving into a period of high pressure.
SATURDAY NIGHT: Trace of snow overnight with light southwest wind, freezing level at valley bottom.
SUNDAY: Broken cloud cover, freezing level at valley bottom, moderate to strong southwest wind, trace of snow possible.
MONDAY: Scattered cloud cover, freezing level at valley bottom, moderate to strong east/southeast wind, no significant precipitation expected.
TUESDAY: A few clouds at dawn with cloud cover increasing after lunch, freezing level at valley bottom, light southwest wind, no significant precipitation expected.
Avalanche Summary
This MIN from the Hankin Saturday has some great photos of natural avalanche activity above the cabin, this is the kind of terrain where we'd expect wind slabs to remain problematic Sunday.
Our field team found similar conditions on Friday at the Onion.
If you do head out in the backcountry, please share your observations to the Mountain Information Network!
Snowpack Summary
The region picked up 10 to 20 cm of new snow Friday afternoon into Saturday afternoon, with a bit of wind out of the south. Previous to this, the region has been pounded by winds which have formed fresh slabs in wind exposed terrain at and above treeline. In more wind protected terrain, the riding has reportedly been epic.
Below 1400m, a thin rain crust exists below this week's new snow. There have been reports of faceting around this crust with previous cold temperatures. A spotty surface hoar layer has been reported down ~100cm in the alpine and treeline.
An early season crust can be found near the base of the snowpack. It has shown reactivity in the past week with large loads (explosives and cornice), creating large avalanches. We don't know how widespread this problem may be, but we are definitely keeping an eye on it, and would be avoiding large features and areas with thin to thick snowpack transitions.
Snowpack depth at treeline ranges from 150-200 cm, with higher values in the western part of the region, tapering to the east.
Terrain and Travel
- Avoid freshly wind loaded terrain features.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
- Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
- Seek out sheltered terrain where new snow hasn't been wind-affected.
Problems
Wind Slabs
Southwest wind has formed the recent storm snow into wind slabs in the alpine and treeline.
Aspects: North, North East, East, South East, South, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
An early season crust near the base of the snowpack was previously reactive to large triggers like cornice failures and explosive control work. This isn't the time for the big committing features, take care to avoid areas with thin to thick snowpack transitions.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 12th, 2021 4:00PM
