Lawinenlagebericht

South Rockies

Dec 3 – 4, 2022Avalanche Canada
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Lawinengefahr

Mon
Tue
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

Cold temps and strong winds continue! Watch for reactive wind slabs at higher elevations. Small avalanches have the potential to trigger deeper weak layers. Assess conditions as you travel and back off at any signs of instability.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible - Likely
    Größe
    1–2

    Recent fresh snow combined with strong west/southwest winds will continue to form reactive wind slabs on north and easterly facing slopes. Avoid snow that feels drum like or hollow. In exposed areas extreme winds may strip the slopes - making for poor travel and riding conditions.

    Small avalanches may trigger a bigger avalanche by 'stepping down' to the weak and faceted crystals buried deeper within the snowpack.

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2.5

    Buried layers of surface hoar and facets have been reportedly been reactive in nearby areas. This layer is widespread throughout the Rockies, and has the potential to produce large avalanches. It will be most reactive where the snow above these layers acts as a slab (as opposed to loose snow) such as wind loaded areas.

    Observations on this layer are currently limited. In times of uncertainty such as this, the best defence is to keep terrain choices conservative and reduce your exposure to avalanche terrain where possible.

Confidence

Low

Avalanche Summary

Early season observations are limited! We expect natural and rider triggered wind slab avalanches to occur throughout this region, from available snow and strong winds.

The last reported avalanches were on November 29. Natural storm slabs up to size 2 were suspected to have failed on a buried surface hoar layer that sits 15-30 cm below the surface before 'stepping down' to weak and sugary facets near the base of the snowpack. Check out this MIN report for more details.

We have very few eyes out there. If you do get out please consider reporting in the MIN.

Snowpack Summary

Upper Snowpack: Strong southwest winds will have redistributed recent snowfall into fresh wind slabs at upper elevations. This new snow sits above harder, wind-affected snow in exposed terrain features and in sheltered areas above more faceted (sugary, weak) snow which may not bond well.

Lower Snowpack: Cold temperatures have weakened and faceted the snowpack. A rain crust sits near the ground.

Total snowpack depths at treeline elevations are 50-80 cm and in the alpine 70-140 cm. In many areas, below treeline elevations remain below the threshold for avalanches.

Weather Summary

Friday Night

Partly cloudy skies overnight with a chance of trace amounts of snowfall. Winds remain strong from the southwest.

Saturday

Mostly clear skies. Winds remain strong from the southwest, becoming extreme near the Crownest Pass and in eastern terrain. Wind speeds drop significantly over the evening. -10 alpine high.

Sunday

Clearing skies with light easterly winds. Alpine high of -10. Possibility of late day flurries.

Monday

Cloud increases overnight with light snowfall expected over the day. Strong westerly winds return. Alpine high -10.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Watch for newly formed and reactive wind slabs as you transition into wind affected terrain.
  • If triggered, wind slabs avalanches may step down to deeper layers resulting in larger avalanches.
  • Choose low-angled, sheltered terrain where new snow hasn't been wind-affected.

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