Lawinenlagebericht

Northwest Inland

Feb 24 – 25, 2023Avalanche Canada
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Lawinengefahr

Sun
Mon
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Kernpunkte

Wind slabs are the main concern. You may find them on a variety of aspects with recent shifting winds.

Triggering a deep persistent slab remains possible, especially in areas with a thin snowpack.

Seek out sheltered and low-consequence terrain for the best and safest riding.

Lawinenprobleme

  • Wind Slabs

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

    Variable winds have redistributed 20 to 40 cm of recent new snow into fresh, reactive wind slabs. Winds today will be from the northwest and southwest, whereas previous wind slabs formed in a reverse loading pattern due to northeast winds. Be sure to assess the snow surface on any aspect you are travelling on for clues of wind effect, like cracking or hollow drum-like sounds.

    Recent avalanche reports also indicate that cornices have destabilized and are able to trigger large wind slab avalanches when they fall.

  • Deep Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    2–3.5

    We continue to receive reports of large deep persistent slab avalanches, failing on facets (weak sugary crystals) near the base of the snowpack. These avalanches have occurred most recently with heavy loads such as cornices or explosives, but have also occurred naturally. They are up to 200 cm deep. Although triggering an avalanche on these deeply buried layers is unlikely, the result would be a large destructive avalanche. Avoid shallow, steep, and rocky start zones at treeline and above where triggering a deep persistent slab could be possible.

Confidence

Moderate

Avalanche Summary

Skiers/riders were able to trigger small wind slab avalanches in the northern parts of the region yesterday. Natural wind slab avalanches also occurred up to size 3, triggered by cornice fall.

The field team saw several natural size 2 wind slabs on many different aspects in the alpine at Seaton yesterday.

At Hudson Bay Mountain, one large deep persistent slab avalanche was triggered by cornice fall in the past 24-48 hours. These avalanches highlight the importance of giving cornices a wide berth and avoiding the overhead hazard they present.

Several size 2-3 explosive controlled deep persistent slab avalanches occurred near Ningunsaw yesterday.

Deep persistent slab avalanches continue to be reported throughout the region at least once a week. They are most often occurring in the alpine or near the top of treeline, around rocky ridgelines and in shallow snowpack areas. This is something to keep in mind when traveling through the backcountry.

If you go into the backcountry this weekend, please consider submitting a MIN report.

Snowpack Summary

Strong northeasterly winds have redistributed snow and formed stiff wind slabs in exposed areas. In sheltered areas, surface faceting due to cold temperatures and/or soft surface snow may remain.

Several crusts, layers of facets, or surface hoar can be found in the top 1.5 meters of the snowpack. This mid-pack is generally showing good strength.

Weak layers of note are facets near the bottom of the snowpack, 150 to 200 cm below the surface.

The total height of snow at treeline is between 200 and 280 cm.

Weather Summary

Thursday Night

Increasing cloud, no accumulation, winds northeast 30 km/h switching to west 40 - 60 km/h, overnight low at treeline of -25 °C.

Friday

Mostly cloudy, trace of snow accumulation, winds northwest 40 km/h gusting to 60 km/h, treeline temperatures -15 to -25 °C.

Saturday

5-15 cm, winds southwest 50 km/h gusting to 70 km/h, treeline temperatures -15 to -25 °C.

Sunday

Cloudy, trace of snow accumulation, winds west 30 km/h, treeline temperatures -12 ºC.

More details can be found in the Mountain Weather Forecast.

Terrain and Travel Advice

  • Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
  • Watch for signs of instability like whumpfing, hollow sounds, shooting cracks or recent avalanches.
  • Be mindful that deep instabilities are still present and have produced recent large avalanches.
  • Avoid areas with a thin or variable snowpack.
  • Use extra caution around cornices: they are large, fragile, and can trigger slabs on slopes below.

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