Bulletin d’avalanche

North Rockies

Mar 28 – 29, 2022Avalanche Canada
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Archivé · expiré 5 years ago

Danger d’avalanche

Wed
Thu
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Points saillants

Start and finish your day early. Warm temperature and sunshine may destabilize the snowpack throughout the day, especially on steep slopes that are baking in the sun. 

The best and safest riding will be in north-facing terrain that is free from cornices overhead. 

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    Wind slabs may be found in wind-loaded terrain in the alpine and treeline, formed by recent snowfall and westerly winds. These wind slabs will be most reactive where they overlie a slick crust.  

    Warm temperatures may cause cornices to become weak. Cornice failures are dangerous on their own, but also have the potential to trigger larger avalanches on the slopes below.

  • Loose Wet

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

    Sun and warm temperatures will weaken the snow surface on sun-exposed slopes, creating wet avalanches out of steep terrain. Watch for wet and heavy surface snow.

Confidence

Moderate - Uncertainty is due to the timing or intensity of solar radiation and its effect on the snowpack.

Weather Forecast

MONDAY NIGHT: Clearing. Freezing level dropping to valley bottom. 20-50 km/h west winds.

TUESDAY: Mainly clear. Freezing level rising to 2000-2500 m in the afternoon. 30-50 km/h southwest winds. 

WEDNESDAY: Cloudy with snowfall, 5-10 cm of accumulation. Freezing level around 1500 m. 20-50 km/h west winds. 

THURSDAY: Cloudy with snowfall, 5 cm of accumulation. Freezing level around 1500 m. 20-50 km/h west winds. 

Avalanche Summary

Several small (size 1-1.5) wet loose avalanches were observed on Sunday at treeline and below. 

On Saturday, a few small (size 1) natural wet loose avalanches were observed from steep terrain below treeline. Several natural cornice failures occurred that did not pull slabs on the slopes below.

Looking forward, riders may be able to trigger wind slabs in lee terrain features in the alpine and exposed treeline, and wet loose avalanches in steep, sun-exposed terrain.

Snowpack Summary

Up to 30 cm of recent snowfall tapers rapidly with elevation. Southwest winds may have formed small pockets of windslab in the alpine and exposed treeline. A refrozen crust can be found below the new snow on all aspects as high as 2400 m. This crust is expected to break down throughout the day on solar aspects and at low elevations with sun and warm temperatures. Below the crust, the top 10-30 cm of the snowpack is moist.

There are no deeper concerns at this time.

Terrain and Travel

  • When a thick, melt-freeze surface crust is present, avalanche activity is unlikely.
  • Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet
  • Pay attention to cornices and give them a wide berth when traveling on or below ridges.
  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • Wind slabs may be poorly bonded to the underlying crust.

Régions couvertes