Bulletin d’avalanche

Kootenay Boundary

Feb 26 – 27, 2023Avalanche Canada
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Danger d’avalanche

Tue
Wed
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

Head out with a storm day mindset - new snow will be increasingly reactive to human triggers.

Step back into conservative terrain as snow accumulates, it likely won't bond well with the wind affected surface below.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–2.5

    Widespread storm slabs will develop overnight Saturday and into Sunday as snowfall accumulates. Avoid large, steep slopes and give wind loaded features space - storm snow needs time to bond with the snowpack below.

    A layer of buried surface hoar may increase reactivity and produce larger avalanches than you expect - this is more likely to be found in sheltered and shaded terrain features.

Confidence

Moderate

Avalanche Summary

This week, slab avalanches were produced to size 2 from natural triggers and accidental rider triggers, and to size 3 from explosive control methods. Activity occurred on all aspects from variable wind loading. Most avalanches occurred within the storm snow or wind loaded features, while a few failed on the buried surface hoar layer.

We expect a natural cycle as storm snow accumulates Saturday night and Sunday.

Snowpack Summary

By Sunday morning around 20 cm of low density storm snow is likely, overlying heavily wind affected surfaces at all elevations (Check out this MIN for wind effect photos). Expect deeper deposits in on north and east facing slopes, from southwest winds.

A layer of surface hoar can be found on shaded slopes, and a sun crust on sun affected slopes buried 30-60 cm deep. Otherwise, the snowpack is generally well consolidated and bonding.

The lower snowpack includes a layer of weak sugary crystals near the ground. These facets are slowly gaining strength and have not produced recent avalanche activity. We continue to track the layer and watch for any signs that it could wake up and produce very large avalanches.

Weather Summary

Saturday Night

Up to 25 cm of snow is expected with moderate southwest winds. Snowfall favors the north of the region, with 10-15 cm expected toward the border. Freezing levels remain below valley bottom.

Sunday

Snow continues with another 10 cm possible. Freezing levels around 600 m. Alpine high of -7 °C with moderate southwest winds.

Monday

Cloudy with sunny breaks possible. Moderate southerly winds ease to light. Freezing levels below valley bottom, alpine high of -5 °C. Possible flurries.

Tuesday

Mostly cloudy with flurries. Light southwest winds. Freezing levels below valley bottom, alpine high of -5 °C.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Storm slab size and sensitivity to triggering will likely increase through the day.
  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Approach steep open slopes at and below treeline cautiously, buried surface hoar may exist.

Régions couvertes