Avalanche Forecast
Regions: Tutshi, Wheaton, White Pass East, White Pass West, Yukon.
Be suspicious of areas where the wind is actively depositing snow. Strong wind can make windslabs in less common areas, like part way down large slopes, and on steep cut banks.
Confidence
Moderate
Avalanche Summary
On Saturday, low elevation wind slabs were reactive to rider triggers. A size 1 was reported triggered by a sled in a MIN report from Fraser.
On Friday, our field team observed natural wind slab avalanches up to size 2 and loose snow sluffing from steep alpine terrain around the White Pass.
Also during the storm last week, a natural avalanche cycle up to size 3 was observed from the highway in the inland areas around Paddy peak. We suspect that some of these may include step-downs to buried weak layers.
Snowpack Summary
Recent snow has been stiffened at the surface in exposed areas and transported into wind slabs by strong outflow wind at all exposed elevations.
The mid snowpack is generally hard with a couple of crusts buried 60+ cm and 100+ cm deep, these have been problematic on north to east aspects as high as 1700 m, where they are covered in an overlying layer of weak surface hoar crystals. In inland areas these weak layers are closer to the surface and are easier to trigger.
At the base of the snowpack large sugary crystals persist.
Weather Summary
Sunday night
Clear. Moderate to strong northerly wind. Alpine temperature -16 ºC.
Monday
Increasing cloud. Snow beginning in the afternoon, up to 5 cm. Low elevation wind easing, upper level wind strong northerly. Alpine temperature -18 ºC warming rapidly in the afternoon to -10 ºC.
Tuesday
A mix of sun and cloud. Strong northerly outflow wind. Alpine high -15 ºC in the morning, cooling through the day.
Wednesday
A mix of sun and cloud. Northerly outflow wind easing. Alpine high -22 ºC.
More details can be found in the Mountain Weather Forecast.
Terrain and Travel Advice
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
- Seek out sheltered terrain where new snow hasn't been wind-affected.
- If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
Avalanche Problems
Wind Slabs
Strong northerly winds will be transporting snow into reactive wind slabs in all exposed terrain especially near ridge crests and sharp breaks in terrain.
Aspects: All aspects.
Elevations: Alpine, Treeline.
Likelihood: Likely
Expected Size: 1 - 2
Persistent Slabs
A weak layer of surface hoar and/or facets buried ~100 cm deep has produced occasional large, widely propagating avalanches on north to east aspects above 1500 m. Some avalanches have been remotely triggered from hundreds of meters away! A layer at this depth may not show obvious signs of instability. Best to avoid steep or unsupported high consequence alpine terrain.
Aspects: North, North East, East, North West.
Elevations: Alpine.
Likelihood: Unlikely
Expected Size: 2 - 3