Avalanche Forecast
Issued: Feb 15th, 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
Watch for fresh wind slabs around ridgelines from overnight westerly winds.
Manage open slopes at treeline with caution, persistent slab avalanches are most likely here. Avalanches are unlikely where a thick surface crust exists.
Summary
Confidence
High - Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
TUESDAY NIGHT: Chance of flurries with moderate northwest winds. Partly cloudy with freezing levels dropping to valley bottom.Â
WEDNESDAY: A mix of sun and cloud. Moderate northwest winds, freezing levels reach 1500m, alpine high of -2.Â
THURSDAY: Increasing cloud. Strong northwest winds. Freezing levels rise toward 2000 m over the day. Alpine high of +2.Â
FRIDAY: Mainly cloudy with isolated flurries. Strong northwest winds. Freezing levels remain around 2000 m. Alpine high +4.
Avalanche Summary
Loose dry sluffing has been reported within the new snow.
A size 1 skier accidental was reported on the late January surface hoar on Monday with limited details. Avalanche activity on this buried persistent weak layer increased last week, with size 1-3 slabs reported at treeline elevations. This layer is now below a thick melt freeze crust in most areas.Â
Snowpack Summary
5-10cm of new snow overlies a variety of surfaces. Higher elevations have been heavily wind effected, and a melt freeze crust exists on solar aspects into the alpine. Lower elevations hold a widespread thick melt freeze on all aspects, surface hoar sits above the crust in sheltered terrain features.Â
The late January interface is buried 20-40 cm deep, and consists of a melt-freeze crust at lower elevations and on solar aspects extending into the alpine. Surface hoar sits above the crust in sheltered areas at treeline and below. This layer is still producing human triggered avalanches and propagation-likely test results.Â
The mid January interface is buried 40-70 cm deep, and consists of a crust, facets, and surface hoar. The snowpack below is well consolidated, with the early December crust/facet persistent weak layer buried 100-200 cm deep. It is currently considered dormant. We expect this layer to become active later this season, check out the forecaster blog for more information.
Terrain and Travel
- Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
- Be aware of the potential for large avalanches due to the presence of buried weak layers.
- Look for signs of instability: whumphing, hollow sounds, shooting cracks, and recent avalanches.
Problems
Wind Slabs
Fresh slabs may form as winds redistribute recent light snowfall. These slabs are more reactive where they overlie buried surface hoar or a smooth crust.
Aspects: North, North East, East, South East, South.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Persistent Slabs
- A layer of surface hoar from late January is buried 20-50 cm deep. On solar aspects and at lower elevations surface hoar sits over a melt freeze crust.
- Another layer of surface hoar/facets over a crust from early January is buried 40-100 cm deep.
Treat sheltered open slopes at a treeline with extra caution where the surface hoar is most likely to be preserved - like cut blocks. Deeper instabilities could be triggered in shallow snow pack areas or by a large load such as a cornice or step down avalanche.
Avalanche activity is less likely where a thick and supportive crust sits on the surface.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Feb 16th, 2022 4:00PM
