Avalanche forecast

Northwest Inland

Jan 27 – 28, 2021Avalanche Canada
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Avalanche danger

Fri
Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Forecast moderate to strong southeast wind will easily blow around recent 5-20 cm of low density snow and may form reactive wind slabs. Wind and soft slabs may be particularly touchy anywhere they sit on top of surface hoar. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1–2

    Assess all slopes for wind slabs as southeast wind increases moderate to strong overnight Tuesday and throughout the day 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 form 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.

Confidence

Moderate - Uncertainty is due to the limited number of field observations. Confidence is due to a stable weather pattern with little change expected.

Weather Forecast

Continued cool temps, increasing southeasterly wind and a mix of clouds, sun and isolated flurries.  

TUESDAY NIGHT: Mostly cloudy with isolated flurries, trace to 2 cm new snow, light to moderate southeast wind, treeline temperatures near -13C.  

WEDNESDAY: Mix of sun and cloud with isolated flurries, trace to 2 cm new snow, moderate to strong easterly wind, treeline temperatures around -15 C.

THURSDAY: Sunny with cloudy periods, light southeast wind, treeline temperatures around -17 C. A mild alpine temperature inversion builds as warm air moves inland with cold air and clouds in valleys.

Friday: Mainly cloudy with isolated flurries, trace to 3 cm new snow, moderate to strong southwest wind, treeline temperatures around -14 C.  

Avalanche Summary

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. Otherwise, no significant avalanche activity has been reported since over a week ago, when there was a cycle of natural wind slab avalanches. 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. Buried sun crust can be found on steep solar. Widespread wind scoured surfaces, older wind slabs in alpine and exposed treeline locations and wind effect extending below treeline in open areas persist. 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.
  • Wind slabs are most reactive during their formation.
  • 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.

Regions covered