Avalanche Forecast
Issued: Feb 8th, 2022 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Persistent Slabs, Loose Wet and Wind Slabs.
ldreier,
Avalanche Canada
Rapid warming as well as rain at lower elevations and snow up high will increase the likelihood of triggering the buried weak layer where it is present and destabilize the snowpack below treeline.
Summary
Confidence
Moderate - Uncertainty is due to how the snowpack will react to the forecast weather. Uncertainty is due to the fact that persistent slabs are particularly difficult to forecast.
Weather Forecast
TUESDAY NIGHT: Cloudy, 5 to 10 cm new snow and rain at lower elevations, light to moderate west wind, alpine temperature -3 C, freezing level 1400 m.
WEDNESDAY: Cloudy, 5 to 10 cm new snow, light to moderate southwest wind, alpine temperature +1 C, freezing level rising rapidly to 2400 m.Â
THURSDAY: Mostly sunny, up to 3 cm new snow, light to moderate west wind, alpine temperature 0 C, freezing level dropping to 1500 m.
FRIDAY: Sunny, light northwest wind, alpine temperature -5 C, freezing level 1300 m.
Avalanche Summary
On Monday, wet loose avalanches below 1000 m were observed. Observations were limited due to visibility.
On Sunday, two natural large avalanches of size 2-2.5 were observed in steep terrain on north and east aspects in the alpine. Several large avalanches released on sun exposed steep slopes. Riders triggered a large size 3 avalanche in the south of the region.
On Saturday, several storm and wind slab avalanches up to size 2.5 were observed at treeline and in the alpine. Most released naturally, and a couple were likely triggered by riders. Skiers triggered a large avalanche remotely in the south of the region (see this MIN report for details - thank you for the report).
Snowpack Summary
The recent storm brought around 30 to 50 cm of snow. The snow formed wind slabs in lee terrain features from strong southwest wind and storm slabs in wind sheltered areas.
The snow will be particularly touchy where it loaded a weak layer of surface hoar crystals. This layer is likely anywhere from 50 to 100 cm deep. Reports suggest that the surface hoar is most prominent in sheltered openings at and below treeline but could extend into wind-sheltered terrain in the alpine. Example terrain features to treat as suspect include the lee side of protected ridges, openings in the trees, cut blocks, and burns. On south aspects, a melt-freeze crust may exist instead of surface hoar.
The lower snowpack is generally strong and well-bonded.
Terrain and Travel
- Extra caution for areas experiencing rapidly warming temperatures for the first time.
- Be aware of the potential for large avalanches due to the presence of buried surface hoar.
- Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
- Uncertainty is best managed through conservative terrain choices at this time.
Problems
Persistent Slabs
The recent snow loaded a buried weak layer of surface hoar crystals. The layer may be found around 50 to 100 cm deep and is most prominent in areas sheltered from the wind at and below treeline. Example terrain features to particularly treat as suspect include the lee side of ridges, openings in trees, cut blocks, and burns.
The buried weak layer was reported to be very active in the Blue River area at all elevations, in the Wells Gray area below treeline and it is present up to treeline at Mica Mountain and around Valemount.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Loose Wet
Rain below treeline will destabilize the snowpack. Expect wet loose avalanches at lower elevations.
Aspects: All aspects.
Elevations: Treeline, Below Treeline.
Likelihood
Expected Size
Wind Slabs
Moderate southwest wind will redistribute 10 to 20 cm new snow on Wednesday and form fresh wind slabs. Previously, strong southwest wind has formed wind slabs in lee terrain features at higher elevations. Wind slabs are especially touchy where they overlie a buried weak layer with surface hoar crystals.
The rapid warming can lead to cornice failures, which might trigger buried weak layers on the slopes below.
Aspects: North, North East, East, South East, North West.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Feb 9th, 2022 4:00PM
