Lawinenlagebericht

Coquihalla

Feb 18 – 19, 2023Avalanche Canada
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Lawinengefahr

Mon
Tue
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Kernpunkte

Avalanches are likely to be triggered by light loads such as skiers in wind-loaded areas at all elevations. Carefully evaluate wind loading as you move through terrain and investigate the bond of wind slabs to the crust below them before committing to an open slope.

Lawinenprobleme

  • Wind Slabs

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

    Southwesterly winds are continuing to redistribute 20 cm of available snow into fresh wind slabs on north and east slopes at all elevations. Wind slabs may be sitting on a crust making them especially reactive and sensitive to skier triggering.

    Expected northerly winds will begin building new and reactive wind slabs in exposed alpine and upper treeline features. Continue to use caution on lee features and watch for areas that have been reverse-loaded and cross-loaded.

    Noted reports of cornice growth and failure of cornice tabs on the north aspect terrain. These growing problems can present as a trigger for windslabs that have formed below.

  • Persistent Slabs

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

    A melt-freeze crust formed in mid-January is widespread throughout this forecast region. The terrain features that present the highest likelihood of triggering are where the snowpack is thin and steep rocky terrain features exist.

Confidence

Moderate

Avalanche Summary

On Thursday, A large (size 2.5) avalanche was observed during a helicopter observation flight. This naturally trigger slab avalanche was approximately 80 to 100 cm deep. It initiated at the ridgetop, 2000 m elevation, and ran 250m in length. This very steep and rocky terrain feature was on a northeast aspect and it is suspected that the avalanche ran on a crust formed mid-January. Noted large (size 2) glide slab activity was confined to steep south aspect rock faces between 1600 and 1800 m elevation.

On Tuesday, clear weather allowed operators to see into higher elevations. Evidence of a widespread avalanche cycle from last weekend's storm was observed throughout the region. Several natural cornice and windslab avalanches were observed to size 2.5. Several loose dry avalanches were observed to size 2 out of steep rocky features. These avalanches were all likely caused by past wind loading, warming, or solar input.

Please continue to post your reports and photos to the Mountain Information Network.

Snowpack Summary

Southwest winds continue redistributing 20 to 35 cm of available snow into lee features at higher elevations. On steep solar surfaces, you will find a thin melt-freeze crust. In sheltered areas, 20 to 30 cm of recent storm snow remains unconsolidated, this overlies an additional 50 cm of past HST that has settled and is well bonded.

A melt-freeze crust formed in mid-January is now buried up to 80-120 cm deep. At the moment this layer appears to be gaining strength though in isolated areas small facets are still found above the crust. The snow below this layer is consolidating nicely. Buried 120-150 cm is a crust, formed near the end of December.

Snowpack depths are just below seasonal averages. Total amounts range from 150 to 300 cm at treeline, but decrease significantly below 1500 m.

Weather Summary

Friday Night

Cloudy with light to moderate snowfall, 5 to 15 cm of accumulation. Winds southwest 30 km/h gusting to 50 km/h. Treeline temperatures -6 °C and freezing levels of 500 m. 

Saturday

Overcast with continued light to moderate snowfall, 5 to 10 cm of accumulation. Winds northwest 30 km/h gusting 50 km/h. Treeline temperatures -3 °C and freezing levels 1000 m.

Sunday

 Cloudy with very light isolated flurries, 1 to 5 cm of accumulation. Winds northwest 20 km/h gusting to 60 km/h. Treeline temperatures -3 °C and freezing levels of 1000 m. 

Monday

Cloudy with moderate to heavy snowfall, 10 to 25 cm accumulation. Winds northwest 50 km/h gusting 80 km/h. Treeline temperature -2 °C. Freezing level 1200 m.

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.
  • Avoid freshly wind loaded features, especially near ridge crests, roll-overs and in steep terrain.
  • Seek out wind sheltered terrain below treeline where you can avoid wind slabs and find great riding.
  • Avoid areas with a thin or variable snowpack.

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