Avalanche Forecast
Issued: Feb 24th, 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.
dboucher,
Avalanche Canada
Recently formed wind slabs are expected to be still reactive to human-triggering in exposed high elevation terrain, especially where they overlie a firm crust.
Summary
Confidence
Moderate - Uncertainty is due to the extreme variability of wind effect on the snowpack. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
A strong ridge of high pressure keeps BC dry until a major weather pattern change takes place beginning this weekend.Â
THURSDAY NIGHT: Becoming partly cloudy after midnight, no precipitation, 5-10 km/h westerly wind, alpine low temperature -10 C, freezing level at valley bottom.
FRIDAY: A mix of sun and cloud, no precipitation, 5-10 km/h southwesterly wind, alpine high temperature -5 C, freezing level at 1000 m.
SATURDAY: Increasing cloudiness with light snow beginning in the afternoon, 1-2 cm, 30-50 km/h southerly wind, alpine high temperature -3, freezing level at 1100 m.
SUNDAY: Snow heavy at times, 15-20 cm, 30-50 km/h southerly wind, alpine high temperature -2 C, freezing level at 1200 m.
Avalanche Summary
On Wednesday, a few natural size 1.5 cornice releases were observed on east aspect but did not trigger slab on the slope below. A skier also triggered a size 1 wind slab on a west aspect wind loaded gully feature.
Snowpack Summary
Recent northerly winds have redistributed the snow above the mid-February crust in exposed high elevation terrain which has formed reactive wind slabs and caused extensive wind scouring. This melt-freeze crust is down around 10-30 cm and reported to exist on all aspects and elevations, except for some of the highest elevation polar aspects. Facets have been observed above the crust on northerly aspects.
The late-January crust/facet/surface hoar interface is buried down 40-100Â cm. This layer was most reactive between 1700 m and 2000 m. While this layer now appears to be dormant through most of the region, it may still be possible to trigger it at upper treeline or lower alpine features on northerly aspects with a large load like a cornice or in shallow snowpack areas.
Terrain and Travel
- Be especially cautious as you transition into wind affected terrain.
- Closely monitor how the new snow is bonding to the crust.
- Be aware of the potential for large avalanches due to the presence of buried persistent weak layers.
Problems
Wind Slabs
Recent strong northerly winds have formed wind slabs in exposed terrain at higher elevations. These wind slabs may be still reactive due to the cold temperatures, especially where they overlie a firm crust.
Aspects: East, South East, South, South West, West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
A weak layer from late-January is down 40-100 cm and was most reactive between 1700 and 2000 m. It is now likely dormant in most areas but still possible to trigger on northerly aspects at upper treeline or lower alpine where the overlying crust from mid-February is thinner and not bridging.
Aspects: North, North East, East, West, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 25th, 2022 4:00PM
