Avalanche Forecast

Issued: Jan 27th, 2021 4:00PM

The alpine rating is moderate, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs.

Avalanche Canada ldreier, Avalanche Canada

Email

Fresh wind slabs and soft slabs may have formed with easterly wind in lee terrain features. They will be particularly touchy anywhere they overlie surface hoar. Assess conditions continually as you travel.

Summary

Confidence

Moderate - Uncertainty is due to the speed, direction, or duration of the wind and its effect on the snowpack.

Weather Forecast

WEDNESDAY NIGHT: Mainly cloudy, light southerly wind, treeline temperatures around -20 C.

THURSDAY: Sunny with cloudy periods, light southerly wind, treeline temperatures around -20 C. A mild alpine temperature inversion builds with warmer alpine temperatures than in the cooler valleys. 

FRIDAY: Mainly cloudy with isolated flurries, trace of new snow, moderate to strong southwest wind, treeline temperatures around -20 C. A mild alpine temperature inversion persists.

SATURDAY: Mainly cloudy with isolated flurries, moderate southerly wind, treeline temperatures around -16 C.

Avalanche Summary

Fresh small wind slabs and sluffing on steep alpine slopes was reported on Tuesday. Isolated large avalanches failed during the weekend storm on recently buried surface hoar in the southwest of the region where recent snowfall amounts were on the higher end (up to 15 cm). A few cornice failures were observed late last week.  

Sporadic deep persistent slab avalanches were reported 1-2 weeks ago (triggered with heavy loads such as explosives and cornices), but deeper weak layers appear unreactive under the current conditions.

Snowpack Summary

5-20 cm recent low density snow has buried surface hoar, which was reported as widespread below treeline and isolated at sheltered treeline and alpine locations. In some areas this new snow was redistributed by easterly winds and formed isolated wind slabs or soft slaps. A buried sun crust can be found on steep solar aspects. The new snow sits on widespread wind scoured surfaces, older wind slabs in alpine and exposed treeline locations and open wind effected areas below treeline. A thick crust exists near the surface below 1000 m. An older isolated surface hoar layer from early January, where preserved, is 20-60 cm deep. 

The lower snowpack has two decomposing crust layers that have been causing a deep persistent slab problem for most of the past month. The upper crust is 70-140 cm deep in the Smithers area and continues to show occasional hard sudden results in snow pits. The deeper crust at the bottom of the snowpack continues to be a problem in shallow ranges like the Babines. These layers should be unreactive under the current conditions, but shallow rocky slopes should still be carefully assessed and approached with caution. 

Large cornices are weakening with cold temperatures.

Terrain and Travel

  • Make observations and assess conditions continually as you travel.
  • Be especially cautious near rock outcroppings, on steep convexities and anywhere the snowpack feels thinner than average.
  • Caution around slopes that are exposed to cornices overhead.
  • Be carefull with sluffing in steep terrain, especially above cliffs and terrain traps.

Problems

Wind Slabs

An icon showing Wind Slabs

Assess all slopes for wind slabs as easterly wind transported loose snow on Tuesday and Wednesday. Wind and soft slabs will be particularly touchy anywhere they overlie surface hoar that was reported to be widespread in many sheltered areas. Reactive wind slabs may have formed in the lee of windy exposed ridge crests, on cross loaded features, on steep alpine slopes and in open areas below tree line. 

Cornice failures from above may trigger an otherwise stubborn deeper wind slab in addition to being a hazard outright.

Aspects: North, North East, South, South West, West, North West.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Jan 28th, 2021 4:00PM