Lawinenlagebericht

Sea To Sky

Jan 13 – 14, 2022Avalanche Canada
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Archiviert · abgelaufen 5 years ago

Lawinengefahr

Sat
Sun
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Kernpunkte

Expect conditions to change as you move higher. Low elevations hold wet snow and higher elevations hold storm slabs that may be reactive to human triggers. Avoid large unsupported slopes - deeply buried weak layers will take time to gain strength.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    2.5–4

    A deeply buried weak layer of sugary facets over a crust produced large naturally triggered avalanches during the last storm with rising freezing levels. Small storm avalanches may step down to these deeper instabilities producing large and destructive avalanches. 

    This layer is most likely to be triggered from thin or variable depth snowpack areas such as wind affected features, ridge crests, and near rocky outcroppings.

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1.5–2.5

    Storm snow above 1700 m is generally bonding well to the snow below. Expect human triggering to still be possible as conditions clear. Expect the greatest hazard to be in wind loaded features around ridgelines from southwest winds.

  • Loose Wet

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

    Expect loose wet avalanches to still be possible to trigger, even after the rain has stopped. More reactive conditions exists where wet snow sits over a smooth crust.

    Watch for where surface snow is heavy and wet. 

Weather Forecast

The wet weather finally exits Thursday. Expect warm temperatures to continue Thursday before finally cooling off for the weekend.

WEDNESDAY NIGHT: Freezing levels peak at 2500m overnight with 5-10mm of rain expected. 

 

THURSDAY: The front exits leaving clearing skies and light precipitation expected in the morning - up to 5mm. Freezing levels sit around 1700 m for the day but peak at 2500m in the late evening, with light easterly winds. 

FRIDAY: Partly cloudy with isolated flurries expected. Winds return to strong southwest. Freezing levels at 1500 m. 

SATURDAY: A mix of sun and cloud with no precipitation expected. Freezing levels dip and stay below 1500m. Moderate westerly winds. 

Avalanche Summary

Naturally triggered wet avalanches were observed to size 2.5 in below treeline terrain features.

Storm slabs to size 2 were triggered naturally and by explosives or skiers at treeline and above where snow was less affected by rainfall. 

Confidence

Moderate - Uncertainty is due to how quickly the snowpack will recover and gain strength.

Snowpack Summary

60-90 cm of mixed precipitation has created a variety of surface snow conditions. Strong southwest winds have created deeper slabs at treeline and alpine elevations on north through east facing slopes. 

At lower elevations the precipitation mostly fell as rain creating a saturated upper snowpack sitting over a melt freeze crust that was observed to 2000 m. As temperatures cool the saturated snow will become a thick surface crust.

This recent precipitation adds to the 100+ cm of snow that has fallen since January 1, which may overly sugary faceted grains that formed during the cold spell in late December.

Around 150 to 250 cm deep, another weak layer of faceted grains may be found above a melt-freeze crust that formed in early December. The layer is most prominent between 1700 and 2100 m. Avalanches on this layer are large, but sporadic and isolated. The most likely place to trigger it would be in thin, rocky snowpack areas. The lower snowpack is well-settled and strong.

Terrain and Travel

  • Continue to make conservative terrain choices while the storm snow settles and stabilizes.
  • Be careful as you transition into wind affected terrain.
  • If triggered loose wet avalanches may step down to deeper layers resulting in larger avalanches.

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