Avalanche Forecast
Issued: Dec 12th, 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.
rbuhler,
Avalanche Canada
Wind slabs are expected to be the primary concern on Monday. The wind is expected to switch directions so wind slabs should be expected on all aspects in exposed terrain.
Summary
Confidence
Weather Forecast
An Arctic ridge of high pressure brings cold and dry conditions to the region for the next few days.
Sunday Overnight: Partly cloudy with a chance of isolated flurries, light to moderate S winds, treeline temperature around -15 °C.
Monday: A mix of sun and cloud with a chance of isolated flurries, moderate to strong NE winds, treeline high around -15 °C.
Tuesday: Mainly sunny, light to moderate NE winds, treeline high around -20 °C.
Wednesday: Mainly sunny, light to moderate SW winds, treeline high around -16 °C.
Avalanche Summary
On Saturday, a report on social media suggests there was an human triggered avalanche in the old Azu area outside Powder King but details on the avalanche are very limited. On Friday, the North Rockies field team reported shooting cracks and were triggering small slabs with ski cuts near treeline in the Pine Pass area.
On Monday, wind slabs are expected to remain reactive to human triggering and natural wind slab avalanches are possible. The wind is expected to switch directions so wind slabs should be expected on all aspects. A lingering deep persistent problem still exists in the south of the region but appears to be gaining strength. This deep weakness is likely creating a low probability/high consequence scenario.
Snowpack Summary
On Friday and Saturday, up to 20 cm of new snow was reported bringing the weekly storm snow accumulation to 40-70 cm. This new snow came in with strong winds from the southwest which formed highly reactive slabs in wind exposed terrain. On Monday, the wind is expected to switch directions and wind slabs should be expected on all aspects. Below the past week's storm snow, some surface hoar had been observed in sheltered areas at and below treeline but this appears to be isolated and has not been reactive in recent days.
The lower snowpack consists of a series of early season crusts. Cold temperatures will have promoted faceting around these crusts. Shallow alpine slopes along the eastern side of the Rockies towards Jasper may have weaker, faceted snow near the ground.
Snowpack depths at treeline range from 60cm-200cm, with the shallower value mainly on the eastern side of the range. The alpine snowpack ranges from 150cm-200cm.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Avalanche hazard may have improved, but be mindful that deep instabilities are still present.
- Avoid shallow, rocky areas where the snowpack transitions from thick to thin.
Problems
Wind Slabs
New wind slab formation is expected on Monday as the wind switches direction and blows from the northeast. Reactive wind slabs should be expected on all aspects in exposed terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
An early season crust at the base of the snowpack has shown reactivity in the southeast corner of the forecast region. While this layer likely needs a heavy trigger like a cornice collapse or smaller avalanche stepping down, human triggering may still be possible on thin rocky slopes in this part of the region.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Dec 13th, 2021 4:00PM
