Avalanche Forecast
Issued: Dec 10th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs and Persistent Slabs.
wlewis,
Avalanche Canada
Wind loaded features continue to be the primary concern. Watch for dense pockets of snow around ridgelines, slabs may sit over a weak layer.
Head to sheltered areas for the best riding conditions.
Summary
Confidence
Avalanche Summary
No new avalanches have been reported on the persistent weak layer, but reports of shooting cracks and whumpfing around treeline elevations are keeping this problem on our minds. With limited field observations there is uncertainty around this layer.
Observations over the week reported small, natural wind slabs size 1-1.5 throughout the region in steep wind affected terrain features on north and east aspects.
Please continue to share any observations of photos on the Mountain Information Network!
Snowpack Summary
Variable winds throughout this region has redistributed the 20-40 cm of snow received this week into pockets of wind loading at higher elevations. In sheltered areas without wind effect, loose dry surface snow is making for great riding conditions.
The snowpack below this is generally weak. A layer of surface hoar, facets, and/or melt-freeze crust can be found down 40-70 cm. This layer is more likely to be reactive where wind distribution has created a cohesive slab over it.
Snowpack depths range from 70 cm at treeline to 140 cm in the alpine. Below treeline snowpack is thin and faceted (weak) making it a challenge to access terrain in many areas.
Weather Summary
Saturday Night
Mostly cloudy with flurries bringing up to 3 cm in the south. Moderate southeast winds. Freezing level below valley bottom.
Sunday
Mostly cloudy. Light to moderate northeasterly winds. Alpine high temperatures around -10. No snowfall expected.
Monday
A mix of sun and cloud with light northerly winds. Alpine high of -10. No snowfall expected.
Tuesday
A mix of sun and cloud with light northerly winds. Alpine high of -10. No snowfall expected.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Seek out sheltered terrain where new snow hasn't been wind-affected.
Problems
Wind Slabs
Wind slabs linger on north through east facing slopes at higher elevations.
Reactivity of these wind slabs will vary depending on how recently they formed (newly formed wind slabs are more reactive, whereas old slabs become harder to trigger) and if wind loading sits over the persistent weak layer, making triggering more likely.
Watch for signs of instability such as whumpfing, cracking, and recent avalanches.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A layer of concern formed in mid-November is composed of faceted grains, surface hoar, and/or a hard crust and can be found down 40 to 70 cm. Each incremental snowfall and wind event is adding an additional load bringing the weak layer closer to its tipping point. As a cohesive slab builds above the weak layer it could quickly become reactive to natural or human triggers.
Aspects: All aspects.
Elevations: Treeline.
Likelihood
Expected Size
Valid until: Dec 11th, 2022 4:00PM
