Avalanche forecast

Northwest Coastal

Mar 14 – 15, 2022Avalanche Canada
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Avalanche danger

Wed
Thu
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Stick to conservative terrain choices and minimize your exposure to overhead hazard as storm totals continue to rise.

Storm snow may sit on a variety of weak surfaces, most concerning near Terrace with large buried surface hoar. 

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    2–3

    Expect strong west/southwest winds to build larger slabs in east facing terrain features. 

    Storm snow may sit over a crust on south facing terrain features, and/ or a surface hoar layer in sheltered terrain features at treeline and above. 

    Reports suggest a layer of buried surface hoar is most widespread in terrain surrounding Terrace.

    Lower elevations will again see mixed precipitation or rain. Avalanches are likely where the surface snow is wet, or where rain breaks down a surface crust. 

Confidence

Moderate - Uncertainties in both the snowpack structure and the weather forecast limit our confidence. Forecast snowfall amounts are uncertain.

Weather Forecast

MONDAY NIGHT: Snow continues with another 10-15 cm possible overnight, Kitimat area may see closer to 30 cm. Freezing levels between 500-1000 m. Strong south-southwest winds. 

TUESDAY: Light snowfall continues throughout the day, with 10-20 cm possible. Moderate to strong southwest winds. Freezing levels around 800 m, alpine high of -2. 

WEDNESDAY: 5-10 cm of snow with mostly cloudy skies. Moderate to strong southwest winds. Freezing levels around 1000 m, alpine high -1.

THURSDAY: Snowfall continues overnight with 10-20 cm expected. Strong southwest winds. Freezing levels around 1000 m, alpine high -1.

Avalanche Summary

On Sunday, storm and wind slabs were natural and human triggered to size 1.5. Several larger avalanches have been reported where storm slabs sit on a buried surface hoar or crust. 

Activity on deeper persistent weak layers has been limited throughout last weekend's storm. Avalanches are unlikely to be human triggered on these layers, but possible with a large trigger such as a storm slab in motion or a large cornice fall.

We expect to see similar human triggered and natural avalanche activity throughout Monday and Tuesday.

Snowpack Summary

40-70cm of recent snow has fallen, with strong southwest winds creating deeper deposits on east facing aspects. Low elevations may hold 10-20 cm of wet/moist snow sitting over a widespread crust on all aspects below 1000 m.

Below the recent storm snow, a melt freeze crust exists on south facing slopes, with surface hoar in sheltered terrain features at treeline and alpine elevations. This has been reactive to human triggers within the last 3 days. Reports suggest the surface hoar is most widespread around Terrace.

Another layer of crust and surface hoar sits 60-100 cm deep, buried in late February. It is most prominent in sheltered terrain features at treeline elevations. This layer has shown limited reactivity within the last week. It is more likely to be triggered by large loads like cornice falls or smaller avalanches in motion. 

A thick rain crust from mid-February is buried 70-110 cm. The snowpack below is well consolidated.

Terrain and Travel

  • Minimize exposure during periods of heavy loading from new snow, wind or rain.
  • As the storm slab problem gets trickier, the easy solution is to choose more conservative terrain.
  • Storm slabs in motion may step down to deeper layers resulting in large avalanches.
  • Potential for wide propagation exists, fresh slabs may rest on surface hoar, facets and/or crust.

Regions covered