Avalanche Forecast
Issued: Jan 27th, 2021 4:00PM
The alpine rating is , the treeline rating is , and the below treeline rating is Known problems include Wind Slabs.
ldreier,
Avalanche Canada
Variable moderate winds may have formed fresh wind slab or soft slabs on Wednesday at all elevations. These slabs sit on a buried surface hoar layer and below 1000 m on a crust.
Summary
Confidence
Weather Forecast
WEDNESDAY NIGHT: Mainly clear, light variable wind, treeline temperatures around -16 C.
THURSDAY: Sunny, light westerly wind, treeline temperatures around -14 C. A mild alpine temperature inversion builds with warmer alpine temperatures than in the cooler valleys.
FRIDAY: Mainly cloudy with scattered flurries, up to 10 cm new snow in the very south of the region, moderate south wind gusting strong, treeline temperatures around -14 C. A mild alpine temperature inversion persists.
SATURDAY: Mainly cloudy with scattered flurries, up to 10 cm new snow, moderate south wind, treeline temperatures around -12 C.
Avalanche Summary
On Tuesday, explosive control in the north produced a few small avalanches in recent snow. Isolated small and large slab avalanches have been reported to have failed on recently buried surface hoar or crust in recent days.
In the northern regions (e.g. Stewart or Ningunsaw), large explosives were able to trigger a couple of very large avalanches on deep persistent layers near the ground last week. Debris are still evident from the widespread avalanche cycle over a week ago with size 1-3 storm slabs (in the south of the region) and size 3-4 deep persistent slabs (in the north of the region).
Snowpack Summary
The 10-20 cm of new snow which fell over the weekend might have been transported with reverse eastern wind on Wednesday and formed fresh soft slabs and wind slabs. This snow sits on a crust below 1000m and surface hoar in sheltered locations at and below treeline. Cold clear temps are perfect for ongoing surface hoar formation and near-surface faceting, which will continue to soften older hard surfaces, develop facets around buried crusts and weaken cornices.
A total of 100-150 cm of settled snow has fallen in January, which has helped strengthen early season weak layers. Deeper layers appear to have gone inactive in the southern part of the region. However, in the northern part of the region (e.g. Bear Pass, Ningunsaw) there has still been regular avalanche activity on weak snow at the bottom of the snowpack with large loads such as explosives or cornice collapses.
Terrain and Travel
- Make observations and assess conditions continually as you travel.
- Recent wind has varied in direction so watch for wind slabs on all aspects.
- Be aware of the potential for larger than expected storm slabs due to the presence of buried surface hoar.
- Watch your sluff: it may run faster and further than you expect.
Problems
Wind Slabs
Variable winds shifting to easterly may have transported the 10-20 cm of recent low density snow and build fresh wind slabs or soft slabs in immediate lee of windy ridge crests in the alpine and at treeline, cross loaded features and open areas below treeline. These slabs will be particularly reactive anywhere snow overlies buried surface hoar or crust. Elsewhere, loose snow avalanches (sluffs) can be expected in all steep terrain.
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Valid until: Jan 28th, 2021 4:00PM
